Al-Qada wal Qadar according to to Ahl al-Sunnah
Question

Could you explain to me the Islamic view of the Divine Will and Decree (al-qada wal qadar)? What should I believe with regard to this topic?
Praise be to Allah.We could talk at length about the Islamic view of the Divine will and decree but to make the subject easier to understand, we will start with an overview of this topic, then explain as much as space permits, asking Allah to benefit us thereby and to accept our efforts. 
What is belief in Al-Qada wal Qadar?
Belief in al-qada (the Divine will) means certain belief that everything that happens in this universe happens by the will and decree of Allah. 
Belief in al-qadar (the Divine decree) is the sixth pillar of faith, and no one’s faith is complete without it. In Sahهh Muslim (8) it is narrated that Ibn ‘Umar (may Allah be pleased with him) heard that some people were denying al-qadar. He said: “If I meet these people I will tell them that I have nothing to do with them and they have nothing to do with me. By the One by Whom ‘Abd-Allah ibn ‘Umar swore, if one of them had gold equivalent to Mount Uhud and he spent it, Allah would not accept it from him unless he believed in al-qadar.” 
Aspects of al-qadar
You should also note that belief in al-qadar is not valid unless you believe in the four aspects of al-qadar, which are as follows: 

Belief that Allah knows all things, in general terms and in detail, from eternity to eternity. Not a single atom is unknown to Him in the heavens or on earth. 
Belief that Allah has decreed all things in al-Lawh al-Mahfuz, fifty thousand years before He created the heavens and the earth. 
Belief that the will of Allah is irresistible and His decree is comprehensive, so nothing happens in this universe, good or bad, but by His will. 
Belief that all that exists was created by Allah. He is the Creator of all beings and the Creator of their attributes and actions, as He says (interpretation of the meaning): 

“Such is Allah, your Lord! La Ilaha illa Huwa (none has the right to be worshipped but He), the Creator of all things” [Al-An’am 6:102] 
Prerequisites of belief in al-qadar
Correct belief in al-qadar also involves believing in the following: 

That the individual has free will by means of which he acts, as Allah says (interpretation of the meaning): 

“To whomsoever among you who wills to walk straight” [At-Takwir 81:28] 
“Allah burdens not a person beyond his scope” [Al-Baqarah 2:286] 

That a person’s will and ability do not operate outside the will and decree of Allah, Who is the One Who has given him that ability and made him able to distinguish (between good and evil) and make his choice, as He says (interpretation of the meaning): 

“And you cannot will unless (it be) that Allah wills the Lord of the ‘Alamin (mankind, jinn and all that exists)” [At-Takwir 81:29] 

That al-qadar is Allah’s plan for His creation. What He has shown us of it, we know and believe in, and what He has hidden from us, we accept and believe in. We do not dispute with Allah concerning His actions and rulings with our limited minds and comprehension, rather we believe in Allah’s complete justice and wisdom, and that He is not to be asked about what He does, may He be glorified and praised. 

This is a summary of the belief of the first generations concerning this important topic. We will discuss some of this in more detail below, asking Allah to help us to say the right thing: 
Meaning of al-qada wal qadar
In Arabic, the word qada means perfection and completion, and the word qadar means evaluating and planning. 
In Islamic terminology, qadar means Allah’s decree of all things from eternity, and His knowledge that they will come to pass at the times that are known to Him and in the specific manner that He has decreed and willed . They will happen the way they are meant to and the way they are created. 
Is there a difference between al-qada and al-qadar? 
Some of the scholars said that there was a difference between them, but perhaps the most correct view is that there is no difference in meaning between al-qada and al-qadar, and that each of them points to the meaning of the other. 
There is no clear evidence in the Quran or Sunnah to indicate that there is a difference between them. The scholars agreed that the one may be applied to the other, but it should be noted that the word qadar is most usually used in the texts of the Quran and Sunnah, which indicates that we must believe in this pillar. And Allah knows best. 
The status of belief in al-qadar in Islam 
Belief in al-qadar is one of the six pillars of faith which were mentioned in the words of the Prophet (peace and blessings of Allah be upon him) when Jibril (peace be upon him) asked him about faith (Iman). He said: “(It is) to believe in Allah, His angels, His Books, His Messengers, the Last Day, and to believe in the Divine will and decree (al-qadar) both good and bad.” Narrated by Muslim, 8. Al-qadar is also mentioned in the Quran, where Allah says (interpretation of the meaning): 
 “Verily, We have created all things with Qadar (Divine Preordainment of all things before their creation as written in the Book of Decrees Al-Lawh Al-Mahfuz).” [Al-Qamar 54:49] 
“And the Command of Allah is a decree determined [qadran maqduran].” [Al-Ahzab 33:38] 
Aspects of belief in al-qadar 
Belief in al-qadar cannot be complete until you believe in the following four aspects of this doctrine: 

Knowledge: this is the belief that the knowledge of Allah encompasses all things and not a single atom in the heavens or on earth falls outside of His knowledge. Allah knew all of His creation before He created them. He knew what they would do by means of His ancient and eternal knowledge. There is a great deal of evidence that points to this such as the verses in which Allah says (interpretation of the meaning):

“He is Allah, beside Whom La ilaha illa Huwa (none has the right to be worshipped but He) the All-Knower of the unseen and the seen. He is the Most Gracious, the Most Merciful.” [Al-Hashr 59:22]
“and that Allah surrounds all things in (His) Knowledge.” [Al-Talaq 65:12] 

Writing: this is the belief that Allah has written the decrees concerning all created beings in al-Lawh al-Mahfuz. The evidence for that is the verse in which He says (interpretation of the meaning):

“Know you not that Allah knows all that is in the heaven and on the earth? Verily, it is (all) in the Book (al-Lawh al-Mahfuz). Verily, that is easy for Allah” [Al-Hajj 22:70]
And the Prophet (peace and blessings of Allah be upon him) said: “Allah wrote the decrees concerning all created beings fifty thousand years before He created the heavens and the earth.” (Narrated by Muslim, 2653) 

Will: this is the belief that everything that happens in this universe happens by the will of Allah. Whatever Allah wills happens and whatever He does not will does not happen. Nothing exists outside of His will. The evidence for that is in the verses where Allah says (interpretation of the meaning):

“And never say of anything, ‘I shall do such and such thing tomorrow.’ Except (with the saying), ‘If Allah wills!’” [Al-Kahf 18:23, 24]
“And you cannot will unless (it be) that Allah wills, the Lord of the ‘Alamin (mankind, jinn and all that exists).” [At-Takwir 81:29] 

Creation: this is the belief that Allah is the Creator of all things, including people’s actions. Nothing happens in this universe but He is its Creator, because He says (interpretation of the meaning):

“Allah is the Creator of all things.” [Al-Zumar 39:62]
“While Allah has created you and what you make.” [Al-Saffat 37:96]
And the Prophet (peace and blessings of Allah be upon him) said: “Allah has made every doer and what he does.” (Narrated by al-Bukhari in Khalq Af’al al-‘Ibad (25) and by Ibn Abi ‘Asim in al-Sunnah (257 and 358); classed as sahih by al-Albani in al-Sahihah, 1637) 
Shaykh Ibn Sa’di (may Allah have mercy on him) said: 
“Just as Allah is the One Who created them – meaning people – He has also created that by means of which they act, namely their abilities and will, then they do various actions of obedience and sin, by the abilities and will which Allah has created.” (Al-Durrah al-Bahiyyah Sharh al-Qasidah al-Taiyyah, p. 18) 
Warning against arguing about issues of al-qadar on the basis of (human) reasoning 
Belief in al-qadar is the real test of the extent of a person’s belief in Allah. It is the true test of how much a person really knows about his Lord and what results from this knowledge of certain and sincere faith in Allah, and His attributes of majesty and perfection. That is because al-qadar raises many questions for the one who gives free rein to his reasoning to try to fully comprehend it.  
There have been many disputes concerning the issue of al-qadar and many people have engaged in debates and misinterpreted the verses of the Quran that mention it. Indeed, the enemies of Islam in all eras have provoked confusion in the Muslims’ beliefs by discussing the issue of al-qadar and stirring up doubts about it. So no one can have true and certain faith except the one who knows Allah by His beautiful names and sublime attributes, submitting to His commands with peace of mind and trusting in his Lord. In that case no doubts or specious arguments can find a way into his heart. 
Undoubtedly this is the greatest proof that belief in al-qadar is more important than belief in the other pillars of faith, and that the human mind cannot independently come to understand al-qadar, because al-qadar is one of the mysteries of Allah in His creation; whatever Allah has disclosed to us in His Book or on the lips of His Messenger (peace and blessings of Allah be upon him) we know, accept and believe in, and whatever our Lord has not told us, we believe in and we believe in His perfect justice and wisdom, and that He is not to be questioned about what He does, but they will be questioned. 
And Allah knows best. May Allah send blessings and peace upon His slave and Prophet Muhammad and upon his family and Companions. 
References: 

A’lam al-Sunnah al-Manshurah, 147; 
Al-qada wal qadar fi Daw il-Kitab wa’l-Sunnah by Shaykh Dr. ‘Abd al-Rahman al-Mahmoud; 
Al-Iman bi’l-Qada’ wa’l-Qadar by Shaykh Muhammad al-Hamd.

For more, please see this category: Belief in the Divine Will and Decree
And Allah knows best.