That's a useful red line.
I actually don't much care if a person is religious, unless they pursue a fundamental version of a religion.
I was simply turning around the frequent claim of religious people that atheists cannot be moral because they don't believe in God. That's absurd. Cleaving to an aged book about a quite different lifestyle for contemporary wisdom is self-evidently silly. It has caused as much damage as any belief in the history of the world.
Even so, there are even some nuggets of wisdom here and there amongst the Bronze Age brutallism in the Bible. Sensible religious people burnish those and set aside the garbage.
But folks who believe all of it are often sanctimonious about morality. And that bubble always wants bursting. They assume they might permit atheists into the circle of morality, instead of wondering if they themselves belong. How often in life the answer is in the question: have you looked in the mirror?
We are moral because evolution gave us the tools to be. It's easy to see why. It's a useful means of surviving within protective communities.