Hello Charlie,
Yes the Bible does say that those that have left the faith should be shunned and not even to sit and eat with them.
The Bible also told the Israelites, when they were under law, to stone their children to death for disobedience and kill anyone who lit a fire on the sabbath.
You have decide whether to take instructions from an ancient book of decide for your self what is a decent way to treat others.
trevor