The denial of resurrection
Denying resurrection after death on the Day of Judgement is contrary to faith, no matter how diayah its forms and examples. It may be a denial of the resurrection of souls and bodies, or it may be a denial of the return of bodies, while acknowledging the return of souls. And sometimes the denial of the Resurrection is by saying that souls are transmigrated/incarnated and transferred to other bodies, and at other times this denial is by denying the resurrection of ignorant souls excluding the knowledgeable ones. [528] Al-Durrah, by Ibn Hazm (p.: 315), Ash-Shifaa, by Iyad (2/290).
Among the reasons for making denial of the resurrection a nullifier of faith is:
1-   Allah Almighty has told that denying the resurrection is infidelity in the Lord of the worlds, thus He the Highest stated, “And if you are astonished, O Muhammad - then astonishing is their saying, "When we are dust, will we indeed be brought into a new creation?" Those are the ones who have disbelieved in their Lord, and those will have shackles upon their necks, and those are the companions of the Fire; they will abide therein eternally.”  Al-Ra’d: 5
Ibn Jareer says, “The Almighty said, “And if you marvel - O Muhammad - at those polytheists who take those which neither harm nor benefit as gods they worship besides me, it is astonishing when they say: ‘If we were dust’ and we were worn out, then we were not existent, ‘will we indeed be brought into a new creation?’ Are we to going to be re-created and brought back to a new creation, as we were before our death? As their denial of the power of Allah, and their rejection of reward, punishment, and resurrection after death … . And His statement, ‘Those are the ones who have disbelieved in their Lord,’ The One Whose mention is Exalted, states, ‘Those who denied the resurrection and rejected the reward and punishment, and said: ‘When we are dust, will we indeed be brought into a new creation?’ They are the ones who denied the power of their Lord and belied His Messenger, and they are the ones who will have shackles on their necks on the Day of Resurrection in the fire of Hell.’ Hence, ‘those are the companions of the Fire;’ He states, ‘they are the residents of the Fire on the day of Judgment.’ ‘They will abide therein eternally,’ He is stating, ‘They will remain in it forever, they will not die in it, and they will not leave it.’” [529] Tafseer of Ibn Jareer, (13/432).
2-   Denial of the resurrection includes incapacitation of the names, attributes of Allah, and their requirements, and a denial of Allah’s knowledge and the perfection of His power and wisdom.
Allah Almighty says, “Did you think that We created you in vain and that you would not be returned to Us?”  Al-Mu’minoon: 115-116
Ibn al-Qayyim states whilst commenting on this ayah, “He made the perfection of His kingdom and His, the Glorified, being the Truth and His being the only God, His being the Lord of the Throne as something necessitates His lordship for all that is below Him, thus nullifying false belief and false judgment, … . His true dominion entails his command and prohibition, reward, and punishment. Likewise, it necessitates the sending of His Messengers, the revelation of His Books, and the resurrection for a Day in which the doer of good will be rewarded for his kindness, and the evildoer for his misdeeds. Whoever denies that has denied the reality of His kingdom and failed to establish for Him the attribute of the True King. Therefore, the one who denied the Resurrection is a disbeliever in His Lord, even if he claims that he acknowledges the Creator of the cosmo, as he does not believe in the True Sovereign who is described with the attributes of majesty, and who is worthy of the attributes of perfection.” [530] Al-Tibyaan fi Aqsaam Al-Quran, (1/247).

Also: Denying the resurrection is a mistrust of Allah, the Mighty and Sublime.
Ibn al-Qayyim states, “And whoever thinks that He will not gather his servants after their death for reward and punishment in an abode in which He will reward the good-doer due to his goodness, and the evil-doer due to his wrongdoing, and He will make clear to His creation the truth of what they differed about, and He will show the worlds His truthfulness, the truthfulness of His messengers, and that His enemies were the liars; then, he has thought badly of Him.” [531] Zaad al-Ma’aad, (3/206).
3-   Denying the resurrection is an apparent denial of the clear ayaat of the Quran proving the resurrection, just as this denial is a refutation of the authentic reports about the occurrence of the resurrection, and it is a denial of what was agreed upon by the call of the Messengers, peace be upon them, and what the heavenly books revealed.
Ibn Abee Al-’Izz Al-Hanafee says, “Belief in the return is evidenced by the Book and the Sunnah, reason, and sound instinct. Allah, Glory be to Him, informed about it in His Mighty Book, established the evidence for it, and responded to those who deny it in most of the surahs of the Quran.” [532] Sharh al-‘Aqeeadah At-Tahawiyah, (2/589).
On the authority of Aboo Hurayrah (may Allah be pleased with him) narrating from the Prophet ? who he said, “Allah states: The son of Adam disaffirmed me, and he did not have the right to do so, and he cursed me, and he did not have the right to do so. As for his denial of Me, he said: ‘He will not bring me back as he created me the first time.’ Whereas the first creation is not easier on Me than bringing him back, and as for his insulting Me, he said: ‘Allah has taken a son. I am the Eternal Unique, I beget not neither was I begotten and there nothing like unto Me.” [533] Narrated by Al-Bukhaaree (4974).
Al-Qastalaanee said, “Allah, the Highest, said, ‘The son of Adam denied Me,’ Kaththaba with emphasis on the letter Thaal, meaning, some of the children of Adam. They are the ones who rejected the resurrection. ‘He did not have the right to do so,’ meaning, denial.” [534] Irshaad al-Sari li Sharh Saheeh al-Bukhaaree, (7/439).
4-   The consensus has been established to confirm the resurrection, just as the scholars of this nation (Ummah) have unanimously agreed on the infidelity of the deniers of the resurrection, and this consensus was narrated by several people of knowledge:
Ibn Hazm says, “The resurrection is true, and the reckoning is true. Allah Almighty will unite souls and bodies on the Day of Resurrection. All of this is unanimously agreed upon by all the people of Islam. Whoever departs from it (this belief) has departed from Islam.” [535] Ad-Durrah fima Yajibu ‘Itiqaaduhu, (p.: 311).
Ibn Abd al-Barr said, “The Muslims have unanimously agreed that whoever denies the resurrection has no faith or testimony, and that is sufficient and suffices, with what is in the Quran confirming the acknowledgment of the resurrection after death; there is no reason to deny that.” [536] Al-Tamheed, (9/116).
Ibn Baaz said: “And thus if he denies resurrection after death, or denies Paradise, or denies Hell, then he disbelieves by the consensus of the Muslims; even if he says: ‘I bear witness that there is no god but Allah, and I bear witness that Muhammad is the Messenger of Allah.’  His denial of these matters is a denial of the Messenger ? and a denial of Allah in what He told in his book.” [537] Fataawaa Noor ‘ala ad-darb, (4/117)

Denial of a promise or threat or mockery of it.
The Noble Quran includes a promise and a threat, so the promise is of forgiveness, contentment, honouring, and entry to heaven, and other types of reward, and the threat is either a curse or anger, or entry to Hell, and other types of punishment.
Allah Almighty stated, “Allah has promised the hypocrites, male and female hypocrites, and the disbelievers the fire of Hell.” At-Tawbah: 68
And Allah, Glory be to Him, said, “Allah has promised the believing men and believing women gardens under which rivers flow.” At-Tawbah: 72
The duty towards the texts of the promise and the threat is to believe in all of them, submit to them, venerate and glorify them, so we believe in Allah Almighty, and what has come from Allah, according to the will of God Almighty; and we believe in the Messenger of Allah, and what came from the Messenger, according to the intention of the Messenger of Allah ?.
Among the denial of promises and threats is the claim of the atheists of the mystics that Heaven or Hell have inner meanings intended only for the bliss of souls or their suffering, or what some of them claim that the people of Hell will enjoy in it just as the people of Paradise will enjoy in Paradise.
Denial of promises and threats and mocking them is one of the nullifiers of faith. For several reasons, including:
1-   Belief in the sacred texts of promises and threats includes acknowledging them, affirming them, venerating them, and honouring them, and this denial contradicts that belief. Denial of heaven and fire as an example contradicts the affirmation of the heart, as it contradicts the words of the tongue, and mocking the texts of promises and threats - including: the texts of heaven and fire - contradicts this veneration and glorification because it contradicts the deed of the heart, which necessitates reverence and glorification of the texts of promises and threats.
2-   That this denial or mockery of the texts of the promise and the threat is a disaffirmation of the Noble Quran where Allah, the Most High, enjoined acknowledging His ayaat and affirming them, and not taking them as a mockery, and also, Allah Almighty has decreed infidelity on those who deny His ayaat, as He threatened such with humiliating punishment, and He Almighty informed that no one is more unjust than he who denies the ayaat of Allah Almighty, and that the gates of heaven will not open for such, and they will not enter Paradise.
Allah, Glory be to Him, called mocking His ayaat disbelief, saying, “Say: Is it Allah and His ayaat and His Messenger that you were mocking at? Do not make excuses.” At-Tawbah: 65-66
3-   That the denial of the sacred texts of the promise and threat and their divestment from their apparent meaning, or ridiculing them include a derision to the prophets, peace be upon them, and their belittling, and falsely accusing them that they might have lied to the interests of the public as alleged by atheists philosophers, while the prophets of peace are truthful and trusted for truth, have delivered the message clearly, established strong arguments against people, they are the best of creation in the sight of Allah Almighty, and the most perfect of creation in knowledge and action, where Allah, the Most High, singled them out with His revelation and chose them from among the rest of the people.
And slandering the prophets is blasphemy and apostasy from Islam. Rather, slandering them is the source of all kinds of blasphemy and the accumulation of misguidance. [538] Al-Saarim Al-Maslool, (2/461).
Also, this denial or mockery of the texts of the promise and the threat leads to disruption of the divine laws, nullification of the commands and prohibitions, manipulation of the legal texts, and doubting them.
Ibn Hazm says, “Everything in the Quran about the matters of Paradise, such as eating, drinking, intercourse, the Houris, immortal children, clothing; and torment in the fire with Zaqqum and boiling water, the shackles and other things – all this is true, then whoever contradicts any of this, then he has left Islam for his contradiction of the Quran, the Sunnah, and the consensus.” [539] Ad-Durrah, (p.: 323).
Aboo Haamid Al-Ghazali said after his Takfeer of those who claim that heaven is a spiritual pleasure, and that Hell is a psychological misery, “What we choose and make certain is that it is not permissible to stop at doing Takfeer of someone who believes in any of that because it is a clear denial of the Lawmaker, and of all the words of the Quran from its beginning to its end. The description of Heaven and Hell has not been mentioned only once or twice, nor is it a metaphor, expansion or figurative, but rather in explicit words concerning which they are not quarrelled or evaded.” [540] Fadhaa’i al-Batiniyyah, (p. 153).