Every monotheist will enter Paradise, so why should the Muslims strive?
Question

Someone said to me: I heard Shaykh ‘Adnaan Ibraaheem say: All the Muslims will enter Paradise, so do whatever you wish. He said to me: Why should we pray, when we will all enter Paradise?
Praise be to Allah.Firstly:
This man, ‘Adnaan Ibraaheem, is not someone who is to be followed regarding religious matters, and his talks should not be listened to, because of the corrupt ideas and beliefs that he promotes.
He is not one of the scholars to whom one should refer; rather his ideas are deviant in terms of knowledge, methodology and belief, as the Ahl as-Sunnah of our time have pointed out.
For more information on him and what he promotes of deviant ideas, please click on the following link:
Secondly:
What is indicated by the texts of the Qur’an and Sunnah, and the salaf (early generations) of this ummah are unanimously agreed upon it, is that no one in whose heart is an atom’s weight of faith will abide in Hell forever. Even if he enters Hell because of his sin, he will remain there for as long as Allah wills, then he will be brought forth therefrom to Paradise.
Al-Bukhaari (44) and Muslim (193) narrated from Anas that the Prophet (blessings and peace of Allah be upon him) said: “Whoever says Laa ilaaha ill-Allah and has in his heart goodness the weight of a grain of barley will be brought out of Hell, then whoever says Laa ilaaha ill-Allah and has in his heart goodness the weight of a grain of wheat will be brought out of Hell, then whoever says Laa ilaaha ill-Allah and has in his heart goodness the weight of an atom (or a small ant) will be brought out of Hell.”
Shaykh Ibn Baaz (may Allah have mercy on him) said:
Whoever dies affirming the oneness of Allah (Tawheed) and not associating anything with Allah will be one of the people of Paradise, even if he commits zina and steals, and even if he commits other sins, such as defiance towards parents, riba (usury), bearing false witness, and so on. For the sinner is subject to Allah’s will; if our Lord wills, He will forgive him, and if He wills, He will punish him according to his sins, if he dies without having repented. And even if he enters Hell and is punished therein, he will not abide therein forever; rather he will be brought forth therefrom to Paradise, after he has been cleansed and purified.
End quote from Fataawa Noor ‘ala ad-Darb (6/51).
See also the answers to questions no. 112113 , 147996 and 170526 .
Thirdly:
For someone to say, “All the Muslims will enter Paradise, so do whatever you want” is a false statement and is contrary to what is  well-known of the religion, which calls and urges people to obey Allah, and warns them against disobeying Him. In fact, it is contrary to the messages of all the Prophets, which call on people to worship Allah and enjoin them to do so. Allah, may He be exalted, says (interpretation of the meaning):
“And We certainly sent into every nation a messenger, [saying], ‘Worship Allah and avoid Taghut [false gods].’ And among them were those whom Allah guided, and among them were those upon whom error was [deservedly] decreed. So proceed through the earth and observe how was the end of the deniers” [an-Nahl 16:36].
Allah sent the Prophets to correct people’s beliefs, deeds and attitudes; the call of Islam sets out guidelines and instructions for the rectification of every aspect of human life:
It was narrated that Abu Hurayrah (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) said: “I have only been sent to perfect good attitude and good manners.” Classed as saheeh by al-Albaani in Saheeh al-Jaami‘ (2349).
The texts which indicate that it is obligatory to obey Allah and obey His Messenger, and warn against doing anything contrary to that, are too many to mention here. For example:
Allah, may He be exalted, says (interpretation of the meaning):
“And obey Allah and the Messenger that you may obtain mercy” [Aal ‘Imraan 3:132]
“And obey Allah and obey the Messenger and beware. And if you turn away - then know that upon Our Messenger is only [the responsibility for] clear notification” [al-Maa’idah 5:92].
And He warns against disobeying Allah and His Messenger, and neglecting His commands. He says (interpretation of the meaning):
“So let those beware who dissent from the Prophet's order, lest fitnah strike them or a painful punishment” [an-Noor 24:63]
“And whoever disobeys Allah and His Messenger and transgresses His limits - He will put him into the Fire to abide eternally therein, and he will have a humiliating punishment” [an-Nisaa’ 4:14]
“It is not for a believing man or a believing woman, when Allah and His Messenger have decided a matter, that they should [thereafter] have any choice about their affair. And whoever disobeys Allah and His Messenger has certainly strayed into clear error” [al-Ahzaab 33:36].
Moreover, it is also contrary to the reason for which Allah created the jinn and mankind. Allah, may He be exalted, says (interpretation of the meaning):
“And I did not create the jinn and mankind except to worship Me” [adh-Dhaariyaat 51:56].
As for this baseless question, “why should we strive, so long as every Muslim will be in Paradise?”,
It may be answered from several angles.
-1- The believer will only attain Paradise by virtue of his own deeds, and not by virtue of his name or heritage. Allah, may He be exalted, says (interpretation of the meaning):
“And We will have removed whatever is within their hearts of resentment, [while] flowing beneath them are rivers. And they will say, ‘Praise to Allah , who has guided us to this; and we would never have been guided if Allah had not guided us. Certainly the messengers of our Lord had come with the truth.’ And they will be called, ‘This is Paradise, which you have been made to inherit for what you used to do’” [al-A‘raaf 7:43]
“The ones whom the angels take in death, [being] good and pure; [the angels] will say, ‘Peace be upon you. Enter Paradise for what you used to do’” [an-Nahl 16:32]
“[They will be told], ‘Eat and drink in satisfaction for what you used to do’” [at-Toor 52:19]
“Indeed, the righteous will be among shades and springs
And fruits from whatever they desire,
[Being told], ‘Eat and drink in satisfaction for what you used to do’” [al-Mursalaat 77:41-43].
-2- If we assume that Allah, may He be exalted, has decreed that someone will enter Paradise, he is also enjoined to strive, and it will be made easy for him to do the deeds of the people of Paradise, so that he will enter it by virtue of his deeds. There is no contradiction between the prior decree of Allah and the religious duties. This is something that is well-known in the religion, that Allah has commanded His slaves to believe in the divine decree (predestination), but at the same time has also enjoined upon them that they should strive.
It was narrated that ‘Ali (may Allah be pleased with him) said: The Prophet (blessings and peace of Allah be upon him) was at a funeral, and he picked up something and started to hit the ground with it, and said: “There is no one among you but his place in Hell or his place in Paradise is already decreed.” They said: O Messenger of Allah, then should we not rely on our destiny and give up striving? He said: “Keep striving, for everyone will be helped to do that for which he was created. As for the one who is among the blessed, he will be helped to do the deeds of the blessed; as for the one who is among the doomed, he will be helped to do the deeds of the doomed. Then he recited the words: “As for he who gives and fears Allah, And believes in the best [reward], We will ease him toward ease” [al-Layl 92:5-7].
Narrated by al-Bukhaari (4949) and Muslim (2647).
-3- It may be said: Yes, no one will enter Paradise except a Muslim, and no one will remain in Hell in whose heart is an atom’s weight of faith, but how can you be certain that Allah will not cast into your heart fitnah, shirk, deviation and misguidance, in requital for your deviating from what He has enjoined and your failing to obey Him? Allah, may He be exalted, has warned those who disobey him, as we have seen above. And Allah, may He be exalted, says (interpretation of the meaning):
“And when they deviated, Allah caused their hearts to deviate. And Allah does not guide the defiantly disobedient people” [as-Saff 61:5].
Each individual should understand that his deeds and his status will only be judged according to how his life ends, and who can guarantee him a good and believing end, if he persists in his deviation and disobedience?
It was narrated that ‘Abdullah ibn Mas‘ood (may Allah be pleased with him) said: The Messenger of Allah (blessings and peace of Allah be upon him) told us, and he is the most truthful one: “The creation of any one of you is put together in his mother’s womb for forty days, then he becomes a ‘alaqah (a piece of thick coagulated blood) for a similar period, then he becomes like a chewed piece of flesh (mudghah) for a similar period, then Allah sends to him an angel who is enjoined to write down four things; it is said to Him: Write down his deeds, his provision, his lifespan, and whether he is doomed (to Hell) or blessed (destined for Paradise). Then the soul is breathed into him. One of you may strive until there is nothing between him and Paradise but a cubit, then the decree overtakes him and he does a deed of the people of Hell. Or he may strive until there is nothing between him and Hell but a cubit, then the decree overtakes him and he does a deed of the people of Paradise.” Agreed upon.
It was narrated from Sahl ibn Sa‘d as-Saa‘idi (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said: A man may do the deeds of the people of Paradise, or so it appears to people, although he is one of the people of Hell, and a man may do the deeds of the people of Hell, or so it appears to people, although he is one of the people of Paradise. Deeds are judged by how they end.” Agreed upon.
And Allah knows best.