@TNT261
"Okay, I don’t get it. How can a GOD make a mistake? "
If you're talking about "OOO" god (Omnipotent, Omniscient, Omnipresent)
Easy way: A god can make "mistake" intentionally and lie to a puny mortal about it.
Hard way: By willing it and applying omnipotence. That requires jumping through a lot of hoops, like temporarily depriving itself of omniscience and omnipotence.
But basically, if OOO god made a mistake, then it willed it.
However, gods in isekai works are greek/roman style - meaning not fully omnipotent and not omniscient, and therefore capable of making an error.