The Gospel is foolishness to many who think they are being saved

I teach Christianity to pupils of various faiths and various attitudes to the Christian gospel. But one thing really disturbs me, and that is this: unbelievers understand the Bible better than believers in my classroom. On one level that's not true - I'm not talking about spiritual receptiveness. But their conceptual understanding of the awesome nature of God ("if there is a God, then if I was standing before him, I'd be scared out of my mind"), holiness and sin ("why doesn't God just spit on us?") and the transcendence of God and its impact on the likeliness, and therefore graciousness, of divine intervention for us ("if there is a God, then why does he bother with tiny little insignificant human beings?") beats the conceptual grasp of many churchgoers, whose God is thoroughly domesticated. No wonder I have two Christian pupils who regard church as stupid: the semi-Christian Christless Christianity they are, by their account of it, receiving probably is.