My 2 Cents Worth:
~ I think Jay Smith makes a very important point. Every Christian is called to do Apologetics at some level. If someone goes around saying that Jesus was a great guru who taught transcendental meditation, you cannot sit idly by. Even if you are not good on your feet, you can still get a book or a website link out to that person for their reading.
However not everyone is called to Polemics and if you are not, then it is better for you to just keep quiet in some situations. I think of how many years ago, Rev. Jerry Falwell on national TV called Muhammaed a terrorist. This resulted in there being riots and such where people were killed. That’s an example of Polemics done improperly. One of the reasons why early missions to India did not do so well were because missionaries engaged in Polemics first, and teaching everything else about the Bible second.
“You mean to tell me that you actually worship that piece of rock? You mean that you actually think that that rock carving is a god? Are you kidding me?”
– No. Unless you are really skillful and know your subject matter in and out and so also the people you are dealing with, unless a lot is in place, you are better off not engaging in Polemics.