Faith is at the very heart of God’s plan for us. By faith alone we are saved. Through it we obtain His free gift of righteousness. But faith doesn’t come naturally to us. The problem is that God doesn’t reveal Himself in a way that our physical senses can perceive Him. I’m not suggesting that God doesn’t allow us to be aware of His presence; He does. But our experience of Him comes by spiritual means—not physical.
        Why would God keep Himself hidden at all? Wouldn’t it be much easier to simply appear and tell us what He wants? Well, that wouldn’t require faith, would it? Our inability to grasp God by our natural senses makes faith indispensable. The Bible says that it’s impossible to please God without it. Yet because faith is so contrary to everything instinctive to our nature, believing God the way He wants will never be all that easy. Apparently He never meant it to be!

From Free from the Power of Sin: the Keys to Growing in God in Spite of Yourself