one that has a chance in a real debate.

good arguments don't in general have a chance in a real debate, because debates are not about reasoning. But that's a nitpick.

I've seen a lot of religious people claiming to have access to strong arguments for theism, but have never seen one myself.

As JoshuaZ asks, you must have a strong argument or you wouldn't think this line of discussion was worth anything. What is it?

I'm going to second JoshuaZ here. There's a lot of disagreement among theists about what the best arguments for theism are. I'd rather not try to represent any particular argument as the best one available for theism, because I can't think of anything that theists would universally agree on as a good argument, and I don't endorse any of the arguments myself.

I would say that most atheists are at least exposed to arguments that apologists of some standing, such as C.S. Lewis or William Lane Craig, actually use.

I mean good arguments.

So why not present what you think these good arguments are?

...[W]hat I'm skeptical of is how many people here have heard a religious argument that actually made them think, one that has a chance in a real debate.

A-causal blackmail, once I thought deeply about why it might be scary. Took about an hour to refute it (to my satisfaction) - whether it would have a chance in a 'real debate': debate length, forum, allotted quiet thinking time and other confounds make me uncertain of your intended meaning.