“Responding to Heresy”
I was debating with someone on a Christian news site a couple weeks ago about T.D. Jakes, and called Jakes a heretic due to his non-trinitarian views. The person accused me of gossip to which I responded that we are to combat lies, and a part of that is exposing false teachers.
J Warner Wallace over at please convince me has a good article on how heretics were combated historically, and how we can use that same model today.