In other words, Theology is practical: especially now. In the old days, when there was less education and discussion, perhaps it was possible to get on with a very few simple ideas about God. But it is not so now. Everyone reads, everyone hears things discussed. Consequently, if you do not listen to Theology, that will not mean that you have no ideas about God. It will mean that you have a lot of wrong ones–bad, muddled, out-of-date ideas. For a great many of the ideas about God which are trotted out as novelties today are simply the ones which real Theologians tried centuries ago and rejected. To believe in the popular religion of modern England is retrogression–like believing the earth is flat.
-C.S. Lewis, 1943