Sometimes I think I'm not smart enough to be an atheist. I can't debate a christian using reason and logic.
I would have to agree with ParkingPlaces, in that if you are, in fact, an atheist, you must be smart enough to be one. We also find it difficult to debate Christians using reason and logic, the two things are just so sharply divorced from their worldview that they often seem to have no effect other than to elicit a lot of defensive preaching as well as lots of fallacies
I was watching a debate recently between William Lane Craig and Christopher Hitchens. From what I understand, WLC is considered to be a difficult Christian to debate. I was open to this possibility. However, after watching the debate, it became clear to me that the reason that he is "effective" at debating is that he is so stubborn, deceitful, and ignorant, yet does it with a tasteful sort of grace and eloquence, like a skilled preacher giving a good sermon. WLC actually challenged Hitch's claim that the word "atheist" means "not a theist" in the same way that "asexual" means "not sexual", as if this had never occurred to him before. How can anyone have a rational argument or possibly "win" against somehow who is so willingly dishonest and manipulative? It's not possible. It's not due to a lack of skill on our side, it's due to a lack of sense on the other. I would postulate that the only reason that WLC is a "successful" debater is that he caters it to an ignorant, believing audience and preys upon their lack of knowledge to make himself look like a genius. I couldn't help thinking, the whole time that I was watching the debate: "This guy is a con, a fraud, and he's good at it, and he knows it, and he exploits it." I could be wrong, but I REALLY got that impression.
Also, some people are just not skilled at debating. There is that possibility. I guess the larger point is that even someone as devastating in a debate as Christopher Hitchens can get frustrated and annoyed with the deceptive tactics and BS of the opposition. Myself, I am much more lacking in confidence in vocal speech as opposed to the written word. Much less comfortable for me face to Yet, in a written medium I can do rather well. Perhaps you just have not found your niche in this area yet?
Best advice I could give is read the posts here, read as much as you can, and keep a link to The Bible Gateway
and The Skeptics Annotated Bible
bookmarked in an easy to find place. They come in handy.