You nailed it: Evangelical Christians have no problem promoting themselves with a message of "believe," then switching to a message of "behave" once they've landed a convert.

The message of "behave" will land Christians (of which I am one) in trouble if we're honest with ourselves. We recognize our message is that rules won't save us, then condemn people because they don't follow the rules. Some choose to be honest and find another church or leave the faith entirely.

This article is a great illustration of what's at the heart of the problem of fundamentalism!