What about the non-religious claim: “There’s not an all-powerful being that is behind everything”? Just as “indefensible”, just as “implausible”, just as “insane”. The sole difference is that it doesn’t involve worship, and therefore categorically isn’t “religious”.

These are axioms, you cannot derive them, you can only derive from them. Saying “my axioms are rational, yours are ‘insane’!” is frankly childish, and speaks to a deep lack of understanding of the essence of reason.