Go on any religiously-themed message board (not a blog; blogs are a special case). Tell them you're an atheist, but that you're open-minded and committed to critically examining your beliefs in a context of good will. Be honest and sincere, but admit that these are merely your beliefs and might well be wrong. Bend over backwards to avoid giving offense, and interpret every comment, even the most blatantly insulting, in a charitable manner. Don't be afraid to over-use opinion qualifiers like "I think", "I suspect", "it seems to me", "according to my experience/understanding", etc.
The only special rule is: Don't talk about abortion; sincere or not, profess indecision and your discomfort with discussing the topic. Abortion makes everyone crazy; it's simply not fair to evaluate the religious on this topic.
This is not at all an insincere experiment. You should be open-minded and committed to critically examining your beliefs in a context of good will; you should discuss your beliefs in a dialectical manner with people who disagree with you. You should at least practice expressing your ideas using a lot of opinion language: Unless you claim omniscience, the opinion language should always at least be implied in your mind.
I've performed this experiment a half-dozen times, and I predict you will receive the following results.
Every time you'll at least one form of Aquinas' five arguments (usually the First Cause argument), the argument from morality, Lewis's trilemma... and you'll get Pascal's Wager. Every time. You'll often get the Fine Tuning version of the Argument from Design. You'll usually get the "atheism is just another religion" argument, and the argument that atheism is irrational because it fallaciously concludes certainty.
Interestingly enough, you'll almost never get the Argument from Design of living creatures: Any venue which supports outright creationism will ban you outright or harass you away before they make any arguments at all. "Guided evolution" is usually considered too tenuous even by its believers to use as a direct apologetic.
Regardless of your demeanor, it will not be long before you are in fact directly insulted. You may well be insulted before you even open your mouth again; otherwise you will be insulted soon after your first rebuttal of a fallacious argument. Forget more than once or twice to explicitly use opinion qualifiers (indeed often on the first omission) and you will be accused of arrogance. You will inevitably be accused of bad faith, ill will, a hidden agenda, intellectual dishonesty, outright stupidity, or moral corruption. Usually all of these.
Message boards are the preferred venue; any venue (unlike an individual's blog) where no one person has privileged status in the discussion. You can also try the experiment on an individual's (or small group's) blog, but you have to be careful to directly engage and count only the privileged person's or persons' responses, and you'll have more variance.
Feel free to actually try this experiment and report back on your results in the comments to the results post; the comments for this post should pertain to analysis and criticism of the experiment itself.