What Is the Evidence that Islam Is True?
Question

I want to be a real Muslim, and that is why I am asking this question: what reason is there for adhering to Islam? In other words, if I were living at the time of the Prophet (blessings and peace of Allah be upon him), and I heard him calling people to this religion, what would motivate me to believe his message and what he brought of the Quran and Sunnah?
Moreover, I do not understand the Quranic challenge (interpretation of the meaning): “Let them then produce a recital like unto it (the Quran) if they are truthful” [at-Tur 52:34]. 
What I understand is that if anyone writes a book on a particular topic, it will be like any other book on the same topic, even if it is different in some minor aspects. So what is so miraculous in the Quran? It may seem strange that such a question comes from a Muslim, but Allah knows best about my intention.
Praise be to Allah.Evidence for the validity of Islam
The evidence for the validity of Islam and the truthfulness of the Prophethood of the Prophet Muhammad (blessings and peace of Allah be upon him) is abundant and can hardly be enumerated. This evidence is sufficient to convince any wise and fair-minded person who is impartially and sincerely seeking the truth. We can sum up some of this proof as follows. 
The evidence of sound human nature
The call of Islam is in accordance with sound human nature, as is indicated by the words of Allah, may He be glorified and exalted (interpretation of the meaning):
“So set you (O Muhammad (blessings and peace of Allah be upon him)) turn your face towards the religion of pure Islamic Monotheism Hanifa (worship none but Allah Alone) Allah’s Fitrah (i.e. Allah’s Islamic Monotheism), with which He has created mankind. No change let there be in Khalqillah (i.e. the Religion of Allah Islamic Monotheism), that is the straight religion, but most of men know not” [ar-Rum 30:30]. 
And the Prophet (blessings and peace of Allah be upon him) said: “There is no child who is not born in a state of fitrah, then his parents make him a Jew or a Christian or a Magian, just as animals bring forth animals with their limbs intact, do you see any deformed one among them?” Narrated by al-Bukhari (1358) and Muslim (2658). 
The words “animals bring forth animals with their limbs intact” mean: just as an animal is born with its limbs intact and free of defects; anything that happens to it of cuts to its ears and so on happens after it is born. 
Similarly, every human is born with an inherent inclination towards Islam, and any deviation from Islam is undoubtedly a departure from sound human nature. Therefore, we never find anything in the teachings of Islam that is contrary to sound human nature. Rather all of its teachings on beliefs and practical matters are in accordance with sound human nature. As for religions and ideologies other than Islam, they include things that are contrary to sound human nature. This is something that is quite clear and apparent to anyone who reflects and ponders. 
Rational evidence
There are many Islamic texts that address reason and direct people to examine the rational proof and evidence, and call upon people of sound reasoning and mature thinking to examine the definitive evidence for the soundness of Islam. 
Allah, may He be exalted, says (interpretation of the meaning):
“(This is) a Book (the Quran) which We have sent down to you, full of blessings that they may ponder over its Verses, and that men of understanding may remember” [Saad 38:29]. 
Al-Qadi ‘Iyad said concerning the miraculous aspects of the Quran:
“In it you will see that there is an explanation of a set of divine laws; it mentions the way of proof based on reason, presents arguments against the misguided followers of different religions and sects, and argues against them on the basis of strong and clear proof, using very easy and concise language. Those who pretend to be clever tried to come up with proof and evidence like that, but they were not able to do so.” (Ash-Shifa (1/390) 
The texts of the revelation do not contain anything that is impossible according to rational thinking or that would be rejected by reason, and the texts never presented an argument that contradicts reason or contradicts any analogy based on rational thinking. Rather the proponents of falsehood never presented any analogy to support their falsehood but the Quran refuted it on the basis of truth and an argument that is based on clear reason. 
Allah, may He be exalted, says (interpretation of the meaning):
“And no example or similitude do they bring (to oppose or to find fault in you or in this Quran), but We reveal to you the truth (against that similitude or example), and the better explanation thereof” [al-Furqan 25:33].                            
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
“Here Allah, may He be glorified, tells us that the disbelievers do not produce any rational argument to support their falsehood but He refutes it on the basis of truth, and presents arguments and evidence and examples that offer a better explanation thereof, are more convincing and give a clearer explanation of the truth than their argument and analogy.” (Majmoo‘ al-Fataawa (4/106) 
One of the examples of rational evidence in the Quran is the verse in which Allah, may He be exalted, says (interpretation of the meaning):
“Do they not then consider the Quran carefully? Had it been from other than Allah, they would surely have found therein much contradiction” [an-Nisa 4:82]. 
In Tafsir al-Qurtubi it says:
“There is no one who speaks a great deal but you will find a lot of contradictions in his words, either in the presentation and wording, or in the meaning, or you will find discrepancies, or there will be untruths. Allah, may He be glorified and exalted, sent down the Quran and instructed them to reflect on it, because they will not find in it any discrepancies in the presentation of ideas, or any flaws in what it promotes, or any contradiction, or any lies in what they are told of matters of the unseen and what they conceal.” (Al-Jami‘ li Ahkam al-Quran (5/290) 
Ibn Kathir said:
“That is, if it were fabricated and made up, as the ignorant polytheists and hypocrites said to themselves, “they would surely have found therein much contradiction” that is, many flaws and discrepancies. In other words, this Book is free of discrepancies and contradictions, therefore it is from Allah.” (Tafsir al-Quran al-‘Azim (1/802) 
Miracles and signs of Prophethood
Allah, may He be exalted, supported His noble Prophet Muhammad (blessings and peace of Allah be upon him) with numerous miracles and tangible signs that pointed to the truthfulness of his Prophethood and the soundness of his message, such as the splitting of the moon for him, the glorification of Allah by food and pebbles in front of him, the springing forth of water from between his fingers, the increasing of food, and other miracles and signs that were seen and witnessed by huge numbers of people, and have been transmitted to us via sahih isnads (sound chains of narration) that reach the level of tawatur. This gives rise to certainty. 
An example of that is that which is narrated in a sahih report from ‘Abdullah ibn Mas‘ud, that he said: We were with the Messenger of Allah (blessings and peace of Allah be upon him) on a journey and our supply of water ran low. He said: “Bring me a little leftover water.” So they brought a vessel in which there was a little water. He put his hand in the vessel, then said: “Come to a blessed, purifying water; and the blessing is from Allah.” And I saw the water springing from between the fingers of the Messenger of Allah (blessings and peace of Allah be upon him). And we used to hear the food glorifying Allah as it was being eaten. (Narrated by al-Bukhari (3579) 
Prophecies
What is meant by prophecies here is what the revelation foretold of matters and events that would happen in the future, whether that was during the lifetime of the Prophet Muhammad (blessings and peace of Allah be upon him) or after his death. 
The Prophet (blessings and peace of Allah be upon him) never foretold anything that would happen in the future, but it would happen exactly as he foretold. This indicates that Allah, may He be glorified and exalted, had revealed and disclosed to him some matters of unseen knowledge that could not be attained except by means of revelation. 
One example of that is the report narrated by Abu Hurayrah, that the Messenger of Allah (blessings and peace of Allah be upon him) said: “The Hour will not begin until a fire emerges in the land of the Hijaz which will illuminate the necks of the camels in Busra.” (Narrated by al-Bukhari (7118) and Muslim (2902)
And it happened exactly as the Prophet (blessings and peace of Allah be upon him) had foretold, in 654 AH – approximately 644 years after his death. This was mentioned by historians, including al-‘Allamah Abu Shamah al-Maqdisi, in his book Dhayl ar-Rawdatayn. He was one of the scholars who lived at the time of this historical incident. 
It was also mentioned by al-Hafiz Ibn Kathir in al-Bidayah wa'an-Nihayah (13/219), where he said: Then the year 654 AH began, in which there appeared fire in the land of the Hijaz by which the necks of the camels in Busra were illuminated, as it says in the agreed-upon hadith. Shaykh al-‘Allamah al-Hafiz Shihab ad-Din Abu Shamah al-Maqdisi spoke at length about that in his adh-Dhayl wa Sharhuhu, based on many letters that came to Damascus from the Hijaz, describing that fire that had been witnessed and seen, and how it emerged, and the story thereof. 
To sum up what Abu Shamah said:
Letters came to Damascus from the Prophet’s City – may the best of blessings and peace be upon its inhabitant – speaking of the emergence of a fire in their land on 5
th Jumada al-Akhirah this year. The letters were written on 5th Rajab, when the fire was still burning, and they reached us on 10th Sha‘ban. Then he said: In the name of Allah, the Most Gracious, the Most Merciful. At the beginning of Sha‘ban 654 AH, letters came to the city of Damascus from the city of the Messenger of Allah (blessings and peace of Allah be upon him) describing a significant event that occurred there, in which there was confirmation of the hadith of Abu Hurayrah in as-Sahihayn, who said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “The Hour will not begin until a fire emerges in the land of the Hijaz which will illuminate the necks of the camels in Busra.” Someone whom I trust from among those who saw it told me that he heard that in Tayma letters had been written by its light. 
He said: We were in our houses during those nights, and in the house of each one of us it was as if there was a lamp, but it had no heat and did not burn, despite its greatness; rather it was one of the signs of Allah, may He be glorified and exalted.”
Qualities and attributes of Prophet Muhammad
One of the greatest proofs of the truthfulness of the Prophethood of the Messenger Muhammad (blessings and peace of Allah be upon him) is his own character and the noble attributes and great manners with which he was blessed, for the Prophet (blessings and peace of Allah be upon him) reached a level of human perfection in terms of good characteristics and attitudes that could only be attained by a Prophet who was sent from Allah. 
There is no praiseworthy characteristic but he promoted it, enjoined it, encouraged it and acted in accordance with it; and there is no blameworthy characteristic but he forbade it, warned against it and was the furthest removed of all people from it. 
His concern for good manners and attitudes reached such an extent that he gave as the reason for his mission the promotion of good attitudes and manners and striving against bad manners and attitudes. In the hadith from the Prophet (blessings and peace of Allah be upon him), it tells us that he said: “I have only been sent to perfect good manners and attitudes.”  (Narrated by Ahmad (8739). Al-Haythami said in al-Majma‘: It was narrated by Ahmad and its men are the men of as-Sahih. 
Al-'Ajlouni classed its isnad as sahih in Kashf al-Khafa. It was also classed as sahih by al-Albani in Sahih al-Jami‘ (2349) 
Miracles are indicative of the truthfulness of the Messenger. He told the people that he had been sent by Allah, may He be exalted, and some of them challenged him to prove that. So Allah, may He be glorified and exalted, supported him with miracles, which are extraordinary events. And he was also granted miracles without anybody challenging him or claiming that he was lying, which served to increase his followers in steadfastness. 
The essence of the call of Prophet Muhammad
The basis of the call of the noble Prophet Muhammad (blessings and peace of Allah be upon him) may be summed up as the aim to build sound beliefs on a sound textual and rational foundation. It is a call to believe in Allah and affirm His oneness in terms of His divinity and lordship. None is deserving of worship except one God, namely Allah, may He be glorified, for He is the Lord, Creator and Sovereign of this universe, Who controls it and disposes of its affairs; He governs it by His command, and is the One Who possesses the power to cause harm or bring benefit, and Who controls the provision of all creatures – and no one has any share of that with Him. Nothing is equal or like unto Him, so He, may He be glorified, is far above having any partners, rivals, peers or equals. 
Allah, may He be exalted, says (interpretation of the meaning):
“Say (O Muhammad (blessings and peace of Allah be upon him)): ‘He is Allah, (the) One. ‘Allah-us-Samad (The Self-Sufficient Master, Whom all creatures need, He neither eats nor drinks). ‘He begets not, nor was He begotten; ‘And there is none co-equal or comparable unto Him’” [al-Ikhlas 112:1-4]
“Say (O Muhammad (blessings and peace of Allah be upon him)): ‘I am only a man like you. It has been inspired to me that your Ilah (God) is One Ilah (God i.e. Allah). So whoever hopes for the Meeting with his Lord, let him work righteousness and associate none as a partner in the worship of his Lord '' [al-Kahf 18:110]. 
The call of the noble Prophet Muhammad (blessings and peace of Allah be upon him) was a call to destroy shirk of all kinds and to rid the two races (of mankind and the jinn) of everything that was worshipped on a basis of falsehood. So there is to be no worship of rocks, stars and graves, or of wealth, whims and desires, or the tyrannical rulers of the earth. 
Rather it is a call that came to liberate humanity from the worship of other people and to bring them forth from the humiliation of idolatry and the oppression of tyrants, and to free them from the captivity of whims and desires. 
This blessed call is regarded as a continuation and affirmation of the previous divinely revealed messages that called to belief in the oneness of Allah. Therefore Islam called people to believe in all the messengers and prophets, and to respect them and venerate them, and to believe in the Books that were revealed to them. A call such as this is undoubtedly true. 
Foretelling of Islam
The Books of the prophets foretold the coming of Islam and the Prophet Muhammad (blessings and peace of Allah be upon him). The Noble Quran tells us of the clear foretelling of the Prophet Muhammad (blessings and peace of Allah be upon him) in the Torah and Gospel, including cases where his name and description are clearly mentioned.
Allah, may He be glorified and exalted, says (interpretation of the meaning):
“Those who follow the Messenger, the Prophet who can neither read nor write (i.e. Muhammad (blessings and peace of Allah be upon him)) whom they find written with them in the Taurat (Torah) (Deut, xviii, 15) and the Injeel (Gospel) (John xiv, 16), - he commands them for Al-Ma’ruf (i.e. Islamic Monotheism and all that Islam has ordained); and forbids them from Al-Munkar (i.e. disbelief, polytheism of all kinds, and all that Islam has forbidden); he allows them as lawful At-Tayyibat ((i.e. all good and lawful) as regards things, deeds, beliefs, persons, foods, etc.), and prohibits them as unlawful Al-Khabaith (i.e. all evil and unlawful as regards things, deeds, beliefs, persons, foods, etc.), he releases them from their heavy burdens (of Allah’s Covenant), and from the fetters (bindings) that were upon them” [al-A‘raf 7:157]
“And (remember) when ‘Isa (Jesus), son of Maryam (Mary), said: O Children of Israel! I am the Messenger of Allah unto you confirming the Taurat ((Torah) which came) before me, and giving glad tidings of a Messenger to come after me, whose name shall be Ahmad” [as-Saff 61:6]. 
In the books of the Jews and the Christians – the Torah and the Gospel – there are still glad tidings that foretell his coming and his message, and describe some of his characteristics, despite the continual attempts to erase and distort these glad tidings. An example of that is what is mentioned in the Book of Deuteronomy, 33:2:
“The Lord came from Sinai and dawned over them from Seir; he shone forth from Mount Paran… ” [New International Version] 
It says in Mu‘jam al-Buldan (3/301):
“Paran is a Hebrew word that is Arabized as Faran. It is one of the names of Makkah that is mentioned in the Torah, and it was said that it is a name for the mountains of Makkah. 
Ibn Makula Abu Bakr Nasr ibn al-Qasim ibn Quda‘ah al-Quda‘i al-Farani al-Iskandarani said: I heard that this refers to the mountains of Paran, which are the mountains of the Hijaz. 
And in the Torah it says: Allah came from Sinai and dawned from Seir and shone forth from Paran. 
His coming from Sinai refers to His speaking to Musa (peace be upon him). His dawning from Seir – which refers to the mountains of Palestine – refers to His sending down the Gospel to ‘Isa (peace be upon him). And His shining forth from the mountains of Paran refers to His sending down the Quran to Muhammad (blessings and peace of Allah be upon him).”
The Noble Quran as a proof of the validity of Islam
This is the greatest of miracles and signs, and the clearest of proof. It is the ultimate proof of Allah against His creation on the Day of Resurrection. It is miraculous from several angles, such as rhetorical, scientific, and legislative, and in the way in which it spoke of future events and unseen matters. 
Commentary on at-Tur 52:34
 With regard to what is meant by the verse (interpretation of the meaning), “Let them then produce a recital like unto it (the Quran) if they are truthful” [at-Tur 52:34], it is a response to those who claimed that the Prophet (blessings and peace of Allah be upon him) was making up the Quran by himself. 
Therefore the Quran challenged them to produce something like it, if they were telling the truth in their claim, because the implication of these claims was that this was something within the capability of human beings. If that was true, then what was preventing them from producing something like it, when they were masters of eloquence and rhetoric? 
Allah challenged the disbelievers to produce something like it, but they were unable to do that, as the Quran tells us (interpretation of the meaning):
“Say: ‘If mankind and the jinns were together to produce the like of this Quran, they could not produce the like thereof, even if they helped one another’” [al-Isra 17:88]. 
And He challenged them to produce ten surahs like it, but they were unable to do that:
“Or, they say, ‘He has forged it.’ Say, ‘Then bring ten chapters similarly forged and call for aid from whom you can besides Allah, if what you say is the truth’” [Hud 11:13]. 
And He challenged them to produce a single surah like it, but they were unable to do that:
“And if you (Arab pagans, Jews, and Christians) are in doubt concerning that which We have sent down (i.e. the Quran) to Our slave (Muhammad (blessings and peace of Allah be upon him)), then produce a Surah (chapter) of the like thereof and call your witnesses (supporters and helpers) besides Allah, if you are truthful” [al-Baqarah 2:23]. 
With regard to the nature of the miracle with which the Quran challenged them , the scholars differed concerning that. There are several views, the most likely of which to be correct is what al-Alusi said: 
“The Quran as a whole, and parts of it, even the shortest surah of it, is a miracle in terms of its composition and eloquence, and its speaking of the unseen, and its harmony with reason and its precise meanings. All these aspects may appear in one verse, or some of them may not be present, such as telling of the unseen. There is no harm in that and no flaw, because what is there is sufficient.” (Ruh al-Ma‘ani (1/29) 
All the proofs mentioned above in general terms may be discussed in much more detail, but we do not have room to do so here. It is more appropriate to read about that in specialised books. Every Muslim is advised to seek knowledge of the Quran and Sunnah, and to study the books of correct ‘aqidah, and to learn about his religion so that he can be a good Muslim and worship his Lord with understanding.
And Allah knows best.