The way to successfully win a debate is to argue your opponent into a corner, where the only way they can get out of the corner is by contradicting themselves. And once you've made your opponent contradict themselves, you've essentially won the debate.
I've been debating for years in my personal life, but I love getting the opportunity to take it public and in person. Once I find something that I can disagree with about another person's beliefs, I often challenge them on it, and, depending on the context of the environment, I will hold my ground until either they give up or I win. I'm extremely competitive when it comes to debating. I've literally had debates with people that have lasted over 6 hours non-stop. And since I'm not a competitive person when it comes to sports, perhaps my way of competing is to debate
That being said I usually don't like the standardized debate format. The best way to debate someone is through a conversation where you can go back and forth, preferably over drinks, but not to the point where either person gets too drunk, because then the debate usually falls into a incoherent shouting match.
Over the years I've become familiar with most of the arguments for the existence of god and I've become somewhat obsessed with refuting them through counter arguments. A good counter argument is one that is logically valid and forces your opponent to contradict themselves in order to refute it. Arguments for god carry so many implications that to successfully refute them, it's a good idea to refute all their implications as well.
For example, in order to make evolution more compatible with religion, some theists take the position that god is not like an engineer, who'd value efficiency, but is instead more like an artist who enjoys the evolutionary process unfolding to create the diversity of species. This artistic god, some theists feel, would prefer something like evolution, rather than a sudden act of efficient creation. But, this artistic god who enjoys guiding and watching the evolutionary process, must at some level be capable of sadism, because the evolutionary process is necessarily miserable to many of the beings it involves. Suffering and death are paramount in evolution, and any being who would take pleasure in designing and watching such a process unfold, must be capable of either indifference, sadism or both. And this I think is a good counter argument to the implication of trying to reconcile evolution with god by claiming god is an artist.
There are numerous examples of fallacious arguments theists make, but none are as humorous as the creationists. I only debate with creationists sparingly because they're seriously not worth my time, but whenever I do their fallacious and intellectually bankrupt arguments become apparent. It's one thing to make a mistake and contradict yourself, we all do that from time to time, but it's another thing when your whole worldview contradicts itself as well as the scientific evidence (that creationists must deny). If a transitional fossil is found, the initial creationist response is to deny it's validity. If that doesn't work, then the creationist will deny that the fossilized animal had any offspring and thus cannot have been an intermediary relative of any current species. And if that doesn't work they'll say that the fossil now produces two gaps on either side of it instead of there being just one.
Creationists will do anything to avoid having to admit that there is plenty of evidence that species have evolved into other species. And their own young earth view forces them actually to adopt the belief that microevolution occurs about 10 times faster than it actually does by believing all the different ethnic groups of humans formed in the last 4-6 thousand years. Science says that took about 40,000 years, not 4,000. So to be a creationist you have to believe evolution works 10 times faster than it does, while you have to deny evolution altogether! Mind-boggling hypocrisy.
Morality is another area where theistic hypocrisy can become apparent. Although you will often hear theists pay lip service to absolute morality, none of them it seems, adhere to it in practice and not even in theory. Every religion contains contradictory morals or morals that have been abrogated, or morals that pertain to specific times, places and people. That means there is no absolute morality; morality is relative to specific situations, people, locations, or the whims of god at any particular moment. Even the Christian concedes that god can command murder, as he does in Numbers 31:2-18 and other biblical passages. This means that even murder has situational relativity.
Perhaps you can say that I'm picking on the low hanging fruit here. I have made it a point to challenge the more "sophisticated" theologies of the more educated theists, and that's what I will continue to do.