"When you come to knowing God, the initiative lies on His side. If He does not show Himself, nothing you can do will enable you to find Him. And, in fact, He shows much more of Himself to some people that to others-not because He has favorites, but because it is impossible for Him to show Himself to a man whose whole mind and character are in the wrong condition. Just as sunlight, though it has no favorites, cannot be reflected in a dusty mirror as clearly as in a clean one."
-C.S. Lewis, Mere Christianity

If you have time, although I feel you should really read the whole book, you can check out the whole chapter from which I got this quote. "The Three Personal God." It is towards the bottom.