Are you in doubt about the Resurrection?.
The believers have no doubt about the resurrection, so they believe that Allah will resurrect them from the graves on the day of resurrection, and they believe that there will be reward and punishment, Paradise and Hellfire, and eternal bliss and eternal misery. But the disbelievers are in doubt about the resurrection as they used to say {Is it that when we die and become dust and bones, indeed, Shall we be resurrected?, and also our former fathers?, Surat Alsaffat, Ayat 16,17}, so the disbelievers denied that Allah will resurrect them from the graves and forgot that Allah is the One who created them the first time as mentioned in Ayat (78,79) of Surat Yaseen {And he cites for Us an example and forgot his creation, he says Who will revive the bones when they are decayed?, Say He will revive them who produced them the first time and He is All-Knower of every creation}, and Allah assures that the second creation is easier for Him than the first creation saying in Aya (27) of Surat Alroom {And He is the One who begins the creation then He repeats it, and it is easier for Him, and to Him is the highest attribute in the heavens and the earth, and He is the Almighty, All-Wise}.
Allah also assures that the creation of the heavens and the earth is greater than the creation of mankind as mentioned in Aya (57) of Surat Ghafir, so Allah calls those who deny the resurrection to reflect on the creation of the heavens and the earth and what is in both of them of the sun, moon, clouds, mountains, rivers, seas, trees, and much more, and if they do so, they would realize that Allah is capable of resurrecting the dead, as Allah says in Aya (33) of Surat Alahqaf {Do they not see that Allah, who created the heavens and the earth, and He was not wearied by their creation, is Able to give life to the dead, yes, indeed, He is All-Powerful over everything}.
And Allah also calls those who doubted the resurrection to reflect on their own creation, as in the creation of Adam from dust and the creation of His progeny in the wombs, and the stages of their growth from birth to death are proofs of the power of their Creator, and Allah gave them a clear sign as evidence of his power to resurrect the dead, as Allah is the One who sends down rain upon the dead earth, and revives it after its death, so the One who gives life to the dead land is Able to resurrect the dead in the same manner, and Allah says in Aya (5) of Surat Alhajj {O people if you are in doubt about the resurrection, then indeed, We created you from dust, then from a sperm-drop, then from a clinging blood, then from an embryonic lump, formed and unformed so that We may make clear to you, and We place in the wombs what We will to an appointed time, then We bring you out as child, then so that you may reach your maturity, and among you is he who is taken in death, and among you is he who is returned to the most abject age, so that he does not know anything after having knowledge, and you see the earth lifeless, then when We send down upon it water, it quivers and grows, and it grows forth of every beautiful pair}.
Unquestionably, Allah did not create mankind in vain, but He created them to worship Allah alone, and not associate anything with Him, as He has stated in Aya (56) of Surat Aldhariyat {And I did not create the Jinn and mankind except that they worship Me}, therefore, Allah has created death and life to test them, to see which of them is best in deeds as mentioned in Aya (2) of Surat Almulk {He who created death and life so that He may test you, which of you is best in deed, and He is Almighty, All-Forgiving}, and Allah has prepared Paradise for those who believe and do righteous deeds, and prepared Hellfire for those who disbelieve and do evil deeds. And Allah will address the companions of Hellfire on the day of resurrection saying as a reprimand {Then Did you think that We created you in vain, and that to Us you would not be returned, Surat Almu'minun Aya 115}.