While I don't disagree with anything you've said, a religion provides a set of limiting principles for someone to develop universal ethics. It can be assumed that someone who identifies as Christian would believe in the Ten Commandments, for example. So when you engage in this person there is a starting point for values to build a society. Without a moral framework, every action or belief becomes an endless opportunity for virtue signaling and the creation of a hierarchy.

The Bible is vast, has terse or "poetic" language that is prone to misinterpretation, has many variants that rely on different translations or canonical versions, and has some big internal contradictions. Calling that a moral framework is lunacy, because anyone can cherry pick whatever they want because it's impossible to get a simple unified message out of it. Hence you have Catholics and Anabaptists, Mormons and Adventists, Christian Identity and zionist evangelicals, Westboro Baptist and faggot Unitarians, all calling themselves Christians.