Back in the "Golden Age of Radio," there was a program about a mysterious vigilante called "The Shadow." Each episode began with this line: "Who knows what evil lurks in the hearts of men? The Shadow knows!"

In Jeremiah 17:9, God makes a statement and then poses a question: "The heart is deceitful above all things, and desperately wicked; who can know it?" The heart--the inner you, what is down deep within you--is devious and dishonest. It's not to be trusted.

Sometimes I hear people explain their actions by saying, "I let my heart dictate what I should do. If I believe in my heart it's right, I go forward." That scares me, and I always remind them that the Bible says the heart is deceitful. There are times when what you feel in your heart turns out to be right, and there are other times when it's wrong. If you're relying solely upon that impulse of emotion, you are open for deception. But if you take what you feel in your heart and test it with the firm foundation of biblical truth, I'd say you're on solid ground.

Implicit in the question "Who can know the heart?" are two answers: "You cannot" and "The Lord can." In fact, God answers His own question in verse 10: "I, the Lord, search the heart, I test the mind, even to give every man according to his ways, according to the fruit of his doings."

God is able to go beyond our actions, our words, and our feelings, and get down to what motivates us. God is always concerned with the motivation that prompted the action. In 1 Samuel 16, when God told the prophet to look for a king, He warned him not to consider appearance. "For the Lord does not see as man sees; for man looks at the outward appearance, but the Lord looks at the heart" (v. 7).

God is able to look within and discern our very intentions. In Psalm 139, David recognizes that God has greater knowledge of him than he has of himself. He says, "Lord, You have searched me and known me. You know my sitting down and my rising up. You understand my thought afar off" (vv. 1-2). What that literally means is, "You know the origin of my thoughts. You know what precipitates them, where they come from."

You've probably had the experience where all of a sudden a weird thought enters your mind, and you think, "Where'd that come from?" You might not know, but God does! He understands your thought processes before they are even formed or come together. He understands them "from afar."

David said, "Such knowledge is too wonderful for me; it is high, I cannot attain it" (v. 6). Then He concluded the psalm with this: "Search me, O God, and know my heart; try me, and know my anxieties; and see if there is any wicked way in me, and lead me in the way everlasting" (vv. 23-24). It's similar to his thought in Psalm 51 that the Lord desires truth in the inward man (see verse 6).

Let that be the prayer for all of us: "Search me, Lord! I want to be found pure in the inner man!" Let's be guided by the truth of God, not by the evil that lurks in our hearts.