They are, after all, probably smarter and more articulate than you. You must think that their position is so indefensible that only a crazy person could defend it.
For the average person, theism/atheism is just a matter of culture.
Among the very smart, successful and articulate (generalizing from 3 extremely smart theist friends and 3 family members), theism indicates certain errors of epistemology.
All 6 smart theists that I know make the following systematic pattern of errors in areas other than theismv (as in, during discussion of empirical questions): 1) over-reliance on inference ("jumping to conclusions" being a common symptom) 2) failure to use parsimony as a discriminating tool.
Additionally, 2 of the 6 do not distinguish rhetoric from argument while thinking, and sometimes accept phlogiston-style explanations, and 1 of the 6 has demonstrated too much trust in authoritative sources such as textbooks and scientific papers (A good scientist always keeps the possibility that the result is wrong and the experiment was flawed in mind) .. although to be fair a lot of equally smart atheist friends have made the same error so that may not be related to theism. Data pending on the others.
In addition to people i know personally, I find that writings from known smart theists follow the same pattern...as do the writings of many atheists. But among people who get it right...well, they' never turn out to be theists.
Sounding "intelligent and articulate" is about being able to make connections, spot internal contradictions within systems, and having a large store of knowledge and vocabulary. You can ascertain someone on that dimension within a few hours of conversation. The above skills can only be ascertained by a more in-depth discussion.
I'm not sure if the skills I listed are a matter of culture or of general cognitive health, but I know that I, at least, was making the same sort of errors (with stuff unrelated to theism) until around 16-19 years of age - at which point I began gradually undergoing a shift. (My metric for "shift" is "does my past self's written work sound stupid or naive to my present self" and I'm 24 now.) That's the age when I started seriously reading scientific literature, but it's also an important stage of brain maturation, so it's hard to say what caused it.
My point is, I don't think smart theists are "stupid", but I do think they have certain systematic recognizable deficits in their thinking which makes their epistemology untrustworthy. People who believe Theism seem to systematically make exactly the sort of errors I would expect from people who believe Theism...a position which is, in essence, a chain of over-long inferences which leads to an unparsimonious conclusion. (It's possible that knowing they were theist colors my observation, of course)
I am about to graduate from one of the only universities in the world that has a high concentration of high-caliber analytic philosophers who are theists. (Specifically, the University of Notre Dame, IN) So as not to miss this once-in-a-lifetime opportunity, I have sent out emails asking many of them if they would like to meet and discuss their theism with me. Several of them have responded already in the affirmative; fingers crossed for the rest. I'm really looking forward to this because these people are really smart, and have spent a lot of time thinking about this, so I expect them to have interesting and insightful things to say.
Do you have suggestions for questions I could ask them? My main question will of course be "Why do you believe in God?" and variants thereof, but it would be nice if I could say e.g. "How do you avoid the problem of X which is a major argument against theism?"
Questions I've already thought of:
1-Why do you believe in God?
2-What are the main arguments in favor of theism, in your opinion?
3-What about the problem of evil? What about objective morality: how do you make sense of it, and if you don't, then how do you justify God?
4-What about divine hiddenness? Why doesn't God make himself more easily known to us? For example, he could regularly send angels to deliver philosophical proofs on stone tablets to doubters.
5-How do you explain God's necessary existence? What about the "problem of many Gods," i.e. why can't people say the same thing about a slightly different version of God?
6-In what sense is God the fundamental entity, the uncaused cause, etc.? How do you square this with God's seeming complexity? (he is intelligent, after all) If minds are in fact simple, then how is that supposed to work?
I welcome more articulate reformulations of the above, as well as completely new ideas.