I think it is the same. Atheist means you don't believe in God. Babies don't believe in God. Or in fact anything outside themselves, as they have no conception of the internal self vs the external world.

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... I am surprised at your insolence in writing to me at all. You know, as I know, that I bought this constituency... may God's curse light upon you and may it make your women as open and as free to the excise officers as your wives and daughters have always been to me while I have represented your scoundrel corporation.
I have the honour to be... your obliged humble servant, Anthony Henley
- MPs reply to constituent, mid 1700s