You pretty well know that your winning the argument, when the other side starts calling you names. That's when the discussion has descended to the elementary school playground. Name-calling is where it was going to end, when they had nothing to start with. I'm a Calvinist in those "debates," because it is premeditated that you're going to win. In fact, mark it down as a "W."
Name-calling characterizes the scoffer. And scoffing is characteristic of an unbeliever. 2 Peter 3 says that scoffers are walking after their own lust. Lust isn't an argument. Wanting it your way doesn't convince anyone. So you scoff.
The genius of name-calling is it works. It's first the false bravado of the weak, keeping the other weak with the tribe. It's gangster method for sake of intimidation. Understand the name-calling represents either laziness or low intelligence. It is carnal convenience. You don't think or you don't feel like it.
You'll see a recent example in an exploding comment thread, best manifested by the word "ketchup." Yes. "ketchup." Professing adults used "ketchup" (here, here, and here). Shame on them. (You'll see that "ketchup" is gone in the links, thanks to the moderators! :-D)