plnelson said, in part:

But as I said to Amos - show me an example of where some religion has changed its core theology because someone convinced them that there was a better theological model.

No surprise there. Those who become convinced of a "better theological model" don't get along (again, no surprise) with the conservatives of the religion, so they move out (in a group or singly), leaving the conservatives in possession of the group identity as "Church of the Pluperfect God" or whatever. The ones who changed join someone else or found their own church/religion under another name. So the perception is that the church hasn't changed, and indeed it hasn't; it has exported the change, as it were.

Dave Oesterreich