This doctrine, recently introduced into Islam by the Jahmiyyah and the Qadariyyah and adopted by those who followed them, is an innovation in the Sacred Law and a patent falsehood in the realm of reason.
As for demolishing the philosophers’ positions that clash with the Qur’an and the Sunnah, praise be to God, this can be done through clear, cogent reasoning from many angles, none of which entails anything but the truth.
The philosophers’ assertion that a particular entity within the universe is eternal necessarily renders that entity the world’s sufficient cause—an idea refuted on several grounds, as explained elsewhere.
Furthermore, the occurrence of a temporal event from an eternal cause in which nothing new has arisen is impossible. If the state of the agent at the moment the effect appears, before it, and during it is absolutely identical, then assigning one specific moment for the emergence of that event would amount to specification without a specifier and production without a producing cause. Nothing could come forth from such a cause, whether mediately or immediately; the unavoidable consequence is that events would have no producer at all—an extreme form of sophistry.
Fleeing from the principle that every contingent must have a cause, they ended up with the far worse claim that the contingent has no producer. What they ran to is vastly more problematic than what they ran from.
It is therefore evident that, were there an eternal cause, its state after bringing the effect into existence could not be identical to its state when it produced it. For if the two states were alike, there would be no reason to privilege the pre-eternal state in which it supposedly acted over any other pre-eternal state, nor the moment of actual production over that of non-production, since all times stand in precisely the same relation to that cause from every angle.