Your challenge: With a POD no earlier than 1930, create a world of today where the fundamentalist religion that generates the greatest amount of political violence is Christianity, with Islamic-associated terrorist attacks rare to nonexistent.
Granted, OTL the friction goes both ways, and there is the odd Christianity-inspired bombing as well (e.g. the 2011 attacks in Norway), but they are rare relative to Islam-inspired ones. The challenge is to reverse this situation as neatly and symmetrically as possible.