Hey everyone, get something by Walter Martin! A talk, an essay, tract or book. This guy is good!
He became a believer out of agnosticism and up until his death was a missionary to the cults, namely LDS and JW's. There is another good resource out there, a book called KINGDOM OF THE CULTS. Apparently a very good book. Pick it up! I will too.
God Bless you all.
PS - don't go against the programming of the cults but don't buy into their doctrines. Remember that you can win an arguement but lose the soul.