When the Bible references the heart, it is referring to the center of your emotions, the center of your desires. In fact, you could say that when the Bible refers to your heart, it is referring to your deepest motives. The Bible teaches that when it comes to your heart — when it comes to the very essence of your motives — you are a complex and complicated being. Jeremiah describes it this way, “The human heart is the most deceitful of all things, and desperately wicked. Who really knows how bad it is?” The answer to Jeremiah's question is God, and only God. The next verse says that God knows our hearts and judges us accordingly. “I, the Lord, search all hearts and examine secret motives.” (Jeremiah 17:9-10)
The truth of Jeremiah’s words is that you cannot know your own heart. And, I should also say, you can't know the heart of anyone else. So don't waste time trying to judge your heart, or the hearts of others. It's a call that you simply aren't equipped to make. You can't see your heart as it really is. Jeremiah’s warning means your heart will play tricks on you. Sometimes it will accuse you, sometimes it will excuse you, and you can't count on it being accurate. That's because it has the capacity to be deceptive above all things. Don't judge yourself. Don't judge your heart. Don't judge your motives. It's not your call.
The only way you can be sure your heart is right is to yield it completely to God. You can analyze it to death and you'll only deceive yourself. You can listen to the opinions of others, and they'll lead you astray. But if you give your heart to God, and trust him with it, he will remove that which is made of stone, and replace it with a heart of flesh — a heart that beats only for him. When all is said and done, your actions and your conduct — more than anything else — reveal the state of your heart. Therefore, the Bible says that God doesn't reward you according to your feelings; he rewards you according to your actions.
People are constantly second-guessing themselves — "Is my heart really pure? Do I really mean it when I say I love God? Am I really, truly thankful?" And if they don't have this certain feeling inside, they start judging themselves, saying, "I must be a hypocrite, or else I wouldn't feel this way." According to the Bible, it's not our feelings that reveal the state of our heart. It's our actions. . But if you are playing church — if you're just going through the motions of a religious life — the solution is not to stay home and do nothing. The solution is to keep doing what is right — keep coming to church, keep making an effort — and along the way ask God to cleanse your heart and purify your motives. “Create in me a clean heart, O God. Renew a loyal spirit within me.” (Psalm 51:10)
Therefore, it is absolutely crucial that your heart be right with God. God's purpose for you is that you give your heart completely to him. Stop worrying about your feelings, and forget about second guessing yourself. Give Jesus your heart, and let your actions follow.