I find it optimistic, to say the least, that each individual can reasonably start from first principles, discover whether there is a Creator, discover if God wants anything from us, and then comply with the requirements of God before the afterlife (if there is one). Atheism is a much more defensible position than a personal deism of any specificity.
Regarding group membership, some organizations are absolutely about that, but the Jesus of the Bible was clearly opposed to people using religion for personal ends. So there are religions that are open to hanging around for the friendship, but biblical Christianity isn't one of them.
> Now, you seem to be arguing that I don't understand the meaning of rational...
I didn't mean any offense. It seemed likely that we didn't have the same definition of 'rational' and it seems even more likely now.
> ...nobody else will care if your axioms aren't shared...
Except people clearly do care. And their response is to establish ingroups, outgroups, promote ignorance, and that's not a good road to go down. I would rather people come to an understanding that everyone is mostly rational, mostly logical, and mostly trying to live a good life. They're normal people that made other choices, in other words.
Regarding nonsensical axioms, axioms can be nonsense if they are inherently contradictory. The axioms we're talking about here pass that hurdle.