In current fundamentalist Christian culture, the standard role is that everybody needs to be Christian or they go to Hell. (Yes, I'm well aware of the semantics of everybody being a sinner and only the Christians being saved.)

Anything blatantly evil or revealed to be evil would play into the assigned role result in more people knowing that God exists and the alternative wants you to do evil things.

So, the most effective thing for the opposition to God to do is be good without God.