I came across this bit of instruction that most of us have neglected in pursuit of evangelism.
Everyone who goes on ahead and does not abide in the teaching of Christ, does not have God. Whoever abides in the teaching has both the Father and the Son. If anyone comes to you and does not bring this teaching, do not receive him into your house or give him any greeting, for whoever greets him takes part in his wicked works. 2 John 1:9-11
This scripture sounds like we shouldn’t even be friendly to them, and if we are, we are participating in their evil deeds! This teaching reminds me of when my preacher invited a well-known speaker from a cult religion to speak in the pulpit on Sunday morning. It caused a bit of decent among our group of Bible students, which in turn, caused the preacher to kick us out of his church. The anger of this preacher welled up like the Incredible Hulk, and rather than help us understand his position, he lashed out at us. According to this, we were right in our disagreement with him.