I've listened to a few debates recently between Christians and atheists: Dinesh D'Souza vs. Christopher Hitchens and William Lane Craig vs. Sam Harris. One thing that struck me was the gap between speech and action on the side of the atheists. That is, the atheists said that they desired to settle the important questions of human life based on reason and evidence, but when it came to actually discussing the issues and trying to settle the questions, the atheists were piling up logical fallacies left and right, and often not actually making arguments at all.
Perhaps the worst offense was the continuous use of straw man arguments. A "straw man" argument is an argument in which you present a weak and/or inaccurate version of your opponent's argument, then easily knock it down (as easily as one could knock over a figure made of straw). Examples abound: Hitchens repeatedly claimed that his opponents believed that anyone who does not believe in their version of God is automatically going to Hell (not true, as least from a Catholic viewpoint); or that God will only answer your requests "if you make the right propitiation and sacrifices" (nope). Indeed, most of his characterizations of basic Christian belief were grossly distorted and misunderstood. But it's much easier to knock down a scarecrow than it is to knock down a soldier.
Other popular non-arguments employed by the atheists included:
Argument by Scoff -- Rather than addressing the reasoning employed by your opponent, you mock their position and insult them. Thus, even in the setting of a formal debate, atheists call belief in God "primitive," "barbaric," "childish," "degrading," "insulting," "irrational," "insane," and the like. This is not an argument. This is playground name-calling.
Argument by Declaration -- Your opponent gives a proof or an argument, and you respond, not by analyzing the argument's premises or logic, but by simply declaring, "The argument doesn't work," or by stating categorically, "There is no convincing argument for the existence of God." It's a circular argument: "There is no convincing argument for the existence of God. Why is that? Because there isn't!" How do I know I am right? Because I just said so!
Bait and Switch -- The atheist begins by saying we must look at reason and scientific observation to determine the question of God's existence. Yet what do they so often appeal to? Crimes of believers, the innocent suffering of children, sad puppy dogs or something. Whoa whoa whoa... what happened to reason and evidence? What happened to debating the logical consistency of the idea itself? To argue "There is no God because some people who believe in God did bad things" is a non sequitur: the one does not follow from the other.
Perhaps I should stop looking to these sorts of debates for anything fruitful, interesting, or thought-provoking. Too often they're just a let-down.