The following is a Buddhist critique of the common theistic idea that God(s) is/are eternal. Eternity means constancy — that something always remains the same. For example, if something eternal is speaking, then it must always have spoken and must always continue to speak, forever. If something spoke eternally, it would also not be able to make more than one sound forever. Although the Abrahamic “I am that I am (or that I will be)” suggests constancy, were an eternal being actually to speak, it would not be able to say more than one sound/word (e.g., “I”), and it would always have been speaking that sound/word and would still be speaking that word today, tomorrow, etc. It could not stop and start speaking, such as to pronounce multiple or even polysyllabic words, because then it would have changed from a time/state when it was not speaking to a time/state when it was speaking and vice versa.
Therefore, as I understand, from a Buddhist perspective, claims that God(s) spoke at great length (e.g., giving entire holy books and many commandments), or that God(s) did some temporary corporeal action (e.g., bringing plagues or floods, destroying cities, writing on stone tablets, etc.) are highly suspect. If they truly are descriptive of a real being — though that being could be immensely big, powerful, old, etc. — that being cannot be eternal, because, by doing those things, it changed.