Arthur Argumentative loves a good "discussion." He doesn't see what he's doing as being argumentative. He just enjoys a lively exchange. The problem is that his aggressive nature offends or scares the other members. Sometimes he even gets a little personal, calling the responses of others "dumb" or "crazy." Note that we're not talking here about a lively, spirited discussion. That's our goal! People will get a bit excited if they're engrossed in a challenging discussion. That's what we want. But Arthur has moved beyond lively and spirited. He's downright rude. How can you deal with someone who steps over the line from discussion to argument?
Pray for him. As with so many of these problems, it's important to take time to regularly and fervently pray, both for Arthur and for your wisdom in handling him. Ask the Lord to show you what might be behind Arthur's belligerence, or at least to give you the wisdom to do no harm as you deal with him.
Clarify the ground rules. If Arthur's attitude isn't posing an immediate problem, wait until the beginning of the next meeting to clarify how you expect group members to relate to one another. This takes the heat off of Arthur and redefines the ground rules for everyone.
Firmly stop the argument. If the indirect approach doesn't work—and it may not—you need to be more assertive in stopping Arthur as soon as he begins to become argumentative. Begin gently, but increase the firmness until he catches on. You might begin by repeating your ground rules in a firmer manner. For example, say, "Let's remember to consider one another's feelings as we discuss this." If that doesn't stop him, next time be more direct. "Arthur, I know that you feel strongly about your position, but you simply ...