I prefer to throw the morality issue in their face, pointing out the utter horrific morals in the bible. I really want people who haven't explored their religion to really think about it. I'm pretty well versed on evolution and I know the basics of cosmology, but I prefer bringing up the political and moral issues of religion. 

That's why I don't just rely on evolution.  The first thing I always ask is "do you have any reason to believe what you just said?"  and let them lead the discusion with me pointing out logical fallicies or facts that are just plain wrong.

The big point with evolution is that I feel like the #1 evidence given by born-agains is that creation proves a creator, and if you can't strike that point down with ease then they just continue to force this issue and you can't really move on to the logic questions.

though i know this will draw criticism from most theists and disagreement from some atheists, i personally consider the argument against the existence of god and the debate over the man-made nature of the bible/religion a done deal. it's just truth against denial, at this point.

my primary focus, now, is the removal of religion from american schools and government. there are others who are more skilled than myself at debating the historical and scientific aspects of atheism.

It really depends upon the individual to whom I am speaking.

For the most part, my own skepticism about why they believe is enough to get the ball rolling.

I fancy myself to be a polymath so any topic they are interested in is fine with me. I listen until they make an error such as a presupposition and then go from there. Ultimately, the conversation comes down to conditioned responses on both of our parts and then I shock them by analyzing that part of the conversation.

Dawkins has been doing that way in the public eye for a couple of years. I've been talking to rednecks, wait staff, and gas station attendants for WAY longer than that. 

I'm generally a defensive atheist. I wait for a theist attack then respond to whatever it is, usually by pointing out where each piece of faulty logic in their argument is. This get's a little repetetive as it seems like they only have a handfull of arguments but it's still fun to recognise each and show its flaws within the context they provide.

I'm qualified as a highschool mathematics and science teacher (although I work as a computer programmer) So I have a broad (although not deep in many areas, my passion is really for mathematics rather than science) knowledge and understanding of science and the logic behind it and some grounding in psychology (mostly developmental psychology) this helps me be the all-rounder I needed to be prepared to counter any argument they present since generally they choose the battle ground. I could probably use better knowledge of history, that's my weakness.

When I do go on the offensive it's usually about the negative efects of religions rather than their falsehood. I focus on the redardation of moral/mental development and individuality and on the stupid and horrible things religion motivates and justifies.  

Apparently I need to brush up on my arguments.

I recently got into a discussion with my mom and sister, who are both liberal theists. And got caught up in the circular logic fight with them cherry picking the bible and claiming most everything in it was meant to be metaphorical. Well, when I pointed out the fallacy and explained you have to take the bible in full and not cherry pick, I got hit with this little tidbit:

"Well I know my dad would be utterly horrified by what you're saying and I hope you're happy with yourself." This coming from my mom, who hasn't quite gotten over her fathers death 20 years ago to lou goerig's disease.

I really wanted to point out that her god would have caused that, but I was simply ignored after that.

I'm usually pretty good at arguing, but with my family its like it falls on completely deaf ears.  

What is my favorite tactic? Any of my close friends will tell you that it is my "One trick poney".

ATTACK THE MAGIC!

What I have learned is that all theists dodge absurdities by attempting to rectify history and science with absurdities.

I've heard a Muslim claiming that a verse in the quran proves Allah's existance because it talks about mountains moving. How does observing an earthquake constitute knowing WHY an earthquake happens?

I've heard everything from "this person existed" to "second law" from multiple apologists and not just from one religion. They all do it.

Tell me how Jesus existing constituts God tapping his friend Gabe on the shoulder saying "Hey Gabe, go tell Marry I have a Barry White album ready for her" Tell me what peer revied medical evidence we have for dead human flesh surviving rigor mortis and carcus decay after 3 days.

When one has their crap dectector set on "If it makes no sense" it is pretty easy.

Although I deal with mainly religion rooted in ancient history, I still apply the same skepticism to things like vampires, ufos, ouiji boards, tarrot cards, Loc ness.

ATTACK THE MAGIC! That is my thing.

I hardly ever get a chance to debate, discuss, or argue with theists face to face. It's pretty rare for me considering where I frequent myself, I suppose I wouldn't mind an encounter or two on a monthly basis. Most all interaction in this sence has been over teh internets.

I generally don't get too deep into discussions, biblical discussions that is, or dive into any other thiest literature. My approach stays within the present as much as possible. I'll remind the thiest that they aren't god, didn't write the book they quote, and can't perform miricles. So there's really not much credibility to what a thiest says regarding the invisible masters of the universe, unless of course they're talking about Heman.

After that it's just separating everything they've entangled and attached with the supernatural, which is really nothing if you think it about it. But you still have to talk about it, and man what a waste of time that is!

Most of my arguments are more slanted toward church-state separation and the need to end the official endorsement of Christianity implicit in slapping big-G God's name into or onto things meant for all Americans, in violation of our first Amendment rights.

Sure, I'll express my opinion that god-belief is ridiculous whenever given the opportunity, but for the most part I'd be happy for people to believe whatever the hell they want at home and in church as long as their religious rules aren't being used to make laws we have to live under. 

I'll have to get much more familiar with the arguments of the resident experts around here before I'll really feel comfortable using them in debate against theists I come across.