I think ultimately Allah is playing a part in this ...
The consensus says not believing in eternal jannah and jahannum is kufr
I once saw a video of Zakir Naik explaining that the life hereafter won't necessarily be eternal so it seems he could have been spreading dangerous beliefs:
1) matters about Islam that everyone knows, which even a child raised among Muslims would know, technically termed maâlum min al-din bi d-darura or ânecessarily known as being of the religionâ;
(2) matters that not everyone knows;
(3) and matters that are disagreed upon even by âthose who know,â the ulema or scholars.
Affirmation or denial of tenets of faith within each category vary in their eternal
consequences because of their relative accessibility, and the individualâs opportunities to find them out.
Things That Everyone Knows
To deny anything of the first category above constitutes plain and open unbelief.
It includes such things as denying the oneness of Allah, the attributes of prophethood, that prophetic messengerhood has ended with Muhammad (Allah bless him and give him peace); the resurrection of the dead; the Final Judgement; the recompense; THE EVERLASTINGNESS OF PARADISE AND HELL; the obligatoriness of the prayer, zakat, fasting Ramadan, or the pilgrimage; the unlawfulness of wine or adultery; or anything else that is unanimously concurred upon and necessarily known by Muslims, since there is no excuse not to know these things in the lands of Islam; though for someone new to the religion, or raised in a wilderness, outside of the lands of Islam, or some other place where ignorance of the religion is rife and unavoidable, their ruling becomes that of the second category. As Imam Nawawi explains:
Any Muslim who denies something that is necessarily known to be of the religion of Islam is adjudged a renegade and an unbeliever (kafir) unless he is a recent convert or was born and raised in the wilderness or for some similar reason has
been unable to learn his religion properly. Muslims in such a condition should be
informed about the truth, and if they then continue as before, they are adjudged
non-Muslims, as is also the case with any Muslim who believes it permissible to commit adultery, drink wine, kill without right, or do other acts that are necessarily known to be unlawful (Sharh Sahih Muslim, 1.150).
ps: above excerpts are from a Sufi Scholar but he's also an Islamic Scholar too so above should be correct as it's nothing to do with Sufism