So, the problem is that Jesus is also the one who is promised to come back riding on clouds of fire and lightning to exact vengeance against unbelievers. Which Jesus you believe in has obvious ramifications (and that doesn't include the versions invented wholecloth from the minds of pastors with agendas).

Now, I'm an ex-Christian and would wholly support removing Revelation from the canon, but the issue is that it remains and informs the worldview of people who claim the name of "Christian."

So I submit that they're actually being good Christians, just not good people.