G.k. Chesterton said this quote

If you try to talk about a truth that’s merely moral, people always think it’s merely metaphorical. A real live man with two legs once said to me: ‘I only believe in the Holy Ghost in a spiritual sense.’ Naturally, I said: ‘In what other sense could you believe it?’ And then he thought I meant he needn’t believe in anything except evolution, or ethical fellowship, or some bilge. . . . -- The Secret of Father Brown