If someone gets reported and banned because they currently believe things a certain way, how will they ever learn? If he's shut out, what choice is left except to go back to his former church?
There are a lot of Christians who are Catholic. They love God and are doing their best to please Him, according to the way they were raised, what they know, what they have been taught. Like it or not, they are our brothers and sisters in Christ.
If anyone's response to this is "Catholics aren't Christian," they'd better do some self-examination.