SAM SAID: “Stephen, if we substituted 'conscience' for 'religious experience' would it make any difference to your arguments? This too is something which people claim to experience, and which leads them to do very different things etc, so why should we trust our conscience?”
STEPHEN REPLIES: Interesting analogy.
Well, first off, you shouldn’t be entirely trusting of your conscience; I’m not of mine. If reason etc. otherwise indicates your moral intuitions are in error, then you should reject them. So, for example, common moral intuitions on homosexuality, the role of women, on other species, etc. – are mistaken. But note there's also good reason to suppose that e.g. your religious experience of an all-powerful, all-good God is mistaken (the evidential problem of evil).
Second, and more importantly, is your moral conscience a quasi-perceptual faculty for determining extra-mental, super-natural facts? That’s what your analogy with the sensus divinitatis requires. But, of course, that our moral conscience is such a quasi-perceptual faculty is highly unlikely. Certainly, you haven't given us any reason to suppose it is.
More probably, our moral conscience is something that has evolved to help us (or our genes) survive and reproduce.
The bottom line is – like a great many philosophers, I am, for good reasons, skeptical of the suggestion that my moral conscience is a quasi-perceptual faculty for revealing non-natural facts. But then I’m similarly skeptical about the suggestion that I’m equipped with a sensus divinitatis - quasi-perceptual faculty for revealing super-natural God-facts.
True, I do often trust the deliverances my moral conscience. But I can do that while being very skeptical of the suggestion that it’s a quasi-perceptual faculty for revealing super-natural facts.
But now notice that you CAN'T similarly trust your religious experience that there’s a God, while remaining skeptical of the suggestion that it’s a quasi-perceptual faculty for revealing super-natural facts.
To argue: "Aha, you consider yourself reasonable in trusting the deliverances of your moral conscience. So you must acknowledge that I am reasonable in trusting my religious experiences!" is to overlook this key difference between moral conscience and sensus divinitatis.
So your analogy fails, I think.