Doubt is the opposite of certainty and is a serious disease of the heart. Once it becomes deep-rooted, it destroys the Muslim's soul through hesitation, suspicion and obsessive diffidence. It also prevents the Muslim from achieving his aims because it makes him unable to make a decision or adopt an opinion; rather it renders him constantly bewildered and reluctant.

　　Doubts drove them to disbelief

　　When Allah The Almighty sent Messengers to their peoples, some of these people were overwhelmed by doubts, and they even acknowledged this. Allah The Almighty Says (what means): {Has there not reached you the news of those before you - the people of Nooh [Noah] and 'Aad and Thamood and those after them? No one knows them but Allah. Their messengers brought them clear proofs, but they returned their hands to their mouths and said, “Indeed, we disbelieve in that with which you have been sent, and indeed we are, about that to which you invite us, in disquieting doubt.” Their messengers said, “Can there be doubt about Allah?”}[Quran 14:9-10]

　　Their doubt and hesitation caused them to disbelieve in Allah The Almighty and in His message; hence, He, the Exalted commanded the Prophet, , to declare to such doubting people that he was following the truth and was certain of what Allah The Almighty had sent him with. Allah The Almighty Says (what means): {Say, [O Muhammad], “O people, if you are in doubt as to my religion - then I do not worship those which you worship besides Allah; but I worship Allah, who causes your death. And I have been commanded to be of the believers.}[Quran 10:104]

　　Doubts about resurrection

　　Muslims are certain that death is not the end of man's existence; rather they believe that there are many hardships that follow. They are certain that Allah The Almighty will resurrect the dead from their graves to be taken to account on the Day of Judgment. However, many non-Muslims do not believe in the Resurrection; instead they are filled with skepticism. Allah The Almighty Says (what means): {Rather, their knowledge is arrested concerning the Hereafter. Rather, they are in doubt about it. Rather, they are, concerning it, blind. And those who disbelieve say, “When we have become dust as well as our forefathers, will we indeed be brought out [of the graves]? We have been promised this, we and our forefathers, before. This is not but legends of the former peoples.”}[Quran 27:66-68]

　　The Noble Quran tells us about one of the most obstinate disbelievers who came to the Prophet, , raising doubts about the issue of the Resurrection. Allah The Almighty Says (what means): {And he presents for Us an example and forgets his [own] creation. He says, “Who will give life to bones when they are disintegrated?” Say, “He will give them life who produced them the first time; and He is, of all creation, Knowing.” [It is] He who made for you from the green tree, fire, and then from it you ignite. Is not He who created the heavens and the earth able to create the likes of them? Yes, [it is so]; and He is the Knowing Creator. His command is only when He intends a thing that He says to it, “Be,” and it is.}[Quran 36:78-82]

　　Hence, when Allah The Almighty resurrects such disbelievers from their graves, they will be certain that what they were doubtful about is indeed a fact. Allah The Almighty Says (what means): {And if you could see when they are terrified but there is no escape and they will be seized from a place nearby. And they will [then] say, “We believe in it!” But how for them will be the taking [of faith] from a place far away? And they had already disbelieved in it before and would assault the unseen from a place far away. And prevention will be placed between them and what they desire, as was done with their kind before. Indeed, they were in disquieting denial.}[Quran 34:51-54]

　　On the other hand, in this life the believers are certain that they will be resurrected on the Day of Judgment. Hence, they supplicate to Allah The Exalted to protect them from the evils of this Day and to be Merciful to them. Allah The Almighty Says (what means):

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