Ah yes, the "no true Scotman" fallacy. You are absolutely correct to say that Evangelical Christians is an oxymoron, but simply cutting them loose and saying "Jesus is coming and we know it" is an attempt to salvage the faith by expelling a radical sect.

Christianity has an unbroken history of crimes and extreme contradictions, and no amount of "not the true faith" will change that. The very foundations of the faith are faulty and the ideology has always been designed to enforce obedience to "God's annointed" clergy and their favored politicians.