Here's an argument I'm toying with. Note: it's very rough -- lots of cleaning up to do, qualifications to make, etc. At this point, I just want to get the basic point on the table and (hopefully) get some feedback.
Some apologists today describe the epistemic force of the case for theism in very modest terms: Christians are within their epistemic rights in believing in God. This sort of view allows that while it can be reasonable to be a theist, it can also be reasonable to be a non-theist.
Apologists who make these sorts of claims are often conservative Christians -- people who believe that, e.g., Paul's epistles are accurately recorded in the New Testament. However, I'm not sure I see how these two views can fit together coherently. For Paul seems to have thought that it's not possible for a normal adult to be a rational non-theist. In fact, he seems to think that such non-belief is only possible by illicitly suppressing the truth about what one knows about God. Here are some of Paul's words in Romans 1: 18-23:
"18The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness, 19since what may be known about God is plain to them, because God has made it plain to them. 20For since the creation of the world God's invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse."
Thus, from the passage above, it seems that Paul thinks that non-believers suppress the obvious truth about an evident God, and that the obviousness of the existence and nature of God is seen through the Creation. And if that's right, then it seems that the cost of the humble claims apologists make about the evidence for theism is holding a view that entails that Paul was wrong: what Paul says in the epistle to the Romans is false. It seems to me, then, that apologists have a choice: (i) defend the claim that the evidence makes the existence and nature of a theistic God evident, or (ii) reject conservative Christianity.
Start with the first option. Taking this route requires apologists to defend the view that the existence and nature of God can not just be seen, but clearly seen (as Paul says in Romans), such that if some don't believe, then they are illicitly suppressing the truth about God. But that's a tough pill to swallow. For even among the Christian philosophers who think the evidence for theism isn't too shabby, few think the evidence is that strong.
The other alternative is to say that Paul was wrong, and that what he said in Romans is false. But again, that's a hard pill to swallow for a conservative Christian. In fact, that seems to be incompatible with conservative Christianity: at a minimum, they have to reject a doctrine taught by the apostle Paul.
In short, it appears that a common contemporary apologetic stance about the evidence for theism is incompatible with conservative Christianity, and that this leads to a dilemma: either the apologist must hold onto Paul's teaching and strengthen their claim about the clarity and strength of the evidence for theism, or retain their modest claim about the evidence and reject Paul's teaching about it. But the former requires holding an implausible view about the strength of the evidence, and the latter requires saying that Paul's teaching in Romans is false. I'm not sure the apologist will be happy with either horn of this dilemma.
In fact, it appears that one can take the argument further and state it as an argument against conservative Christian theism:
1. Either the existence and nature of God are clearly seen through the creation or the apostle Paul was wrong.
2. The existence and nature of God are not clearly seen through the creation (it's possible to survey the evidence for theism, and yet rationally disbelieve, or at least suspend judgement).
3. Therefore, the apostle Paul was wrong. (from 1 and 2)
4. If the apostle Paul was wrong, then conservative Christian theism is false.
5. Therefore, conservative Christian theism is false. (from 3 and 4)
This argument is stronger than the standard argument from divine hiddenness. For the latter is open to the Skeptical Theist reply that for all we know, God has reasons for remaining hidden, and these reasons are beyond our ability to grasp. But on the current argument, the NT seems to leave no room for this, as the NT seems to commit the conservative believer to the thesis that in fact God is not hidden; the evidence for his existence is not only seen, but clearly seen.
 Of course, such a view is compatible with the view that the evidence for theism is much stronger than that. However, as I will argue below, conservative Christians are committed to the stronger, latter sort of view qua conservative Christians.
 For simplicity's sake, I leave out the disjunct that the New Testament inaccurately reports what Paul said on the matter, as that option also entails that conservative Christian theism is false.