When you are talking with someone who is trying to pigeon hole you, i.e. force you in to a small perspective they have, I've found it's better to be defensive than offensive.
Actually, I think this is probably the best all-round advice, even for physical confrontations. Some (my knowledge is weak here) martial arts make use of defensive positions to overcome an attacker.
In other words, if someone is attacking you, you don't also take the offensive, instead you use his offensive energy and momentum as the means to defend yourself. In the physical world this can mean lifting your knee up in front of you as he rushes towards you, then he gets it in the groin.
Another defensive move I've seen is when the offensive person attacks, the victim moves out of the way at the last moment and grabs part of the attacker somehow; as he goes past the victim, the attacker pivots on whatever part was grabbed and is brought painfully to the ground. At least that's how I've seen it done in demonstrations.
I am not saying you should try to bring the offensive arguer painfully to his or her knees, figuratively or literally. I am saying that when you are being verbally attacked it's best to stay on the defensive as opposed to going on the offensive. Many times the attacker is just looking for an excuse to escalate the argument and by you staying defensive, you can thwart that.
Maybe you know a few people who consistently try to pick fights. Intellectual conversation where turns are taken, and one talks calmly seems out of the question to them. They don't seem interested in analyzing a situation and seeking truth, but implicating you. They may only seem interested in verbally abusing you with insults, mischaracterizations, and lies; as well as hogging the conversation.
I've found the best way to keep my sanity and prevent the person from growing even more offensive, is to just be defensive in what I say.
Unfortunately it often seems the offensive attackers have a too-small view of the world and of the person they are attacking; often trying to force you in to one of two views (see the article "One Dimensional World?") as though the world was black and white.
You will notice they usually interrupt you and instantly try to contradict you, or attack you; this is their "defense" mechanism against thinking.
Sorry to say, but I think some painful life-lesson is the only way they are going to grow. And I don't think it's your or my place to dole that out. Only God knows the best time and place to do so.
So in the mean time, just take a defensive stance. And pray for them. Repay their meanness with kindness.