My grandfather was an atheist until the day he died. On that day he changed his mind. He was 100.
Atheists don’t not believe in God. They simply wish that God didn’t exist. Usually because it means they would have to change the way they’re living in some way, and they really don’t want to. They have another god, but they either don’t realize it or they don’t want to admit it.
Did he suddenly become an agnostic? A Zoroastrian? A Buddhist?
Inquiring minds, etc.!
Regards,