The word "heart" actually has a much broader meaning in the Bible than it usually does today, and once you understand this, you'll see why inviting Jesus into our heart is so important.
In the Bible, the word "heart" refers to our whole inner being: our minds, our wills, our emotions, our motives, our moral character -- everything. The "heart" isn't simply the physical organ that pumps our blood; it is everything that makes us what we are. One Bible passage calls it "your inner self" (1 Peter 3:4). When Samuel was sent to seek out a new king, God reminded him that "Man looks at the outward appearance, but the Lord looks at the heart" (1 Samuel 16:7).
What does God see when He looks at our hearts? The Bible's picture isn't flattering -- because it tells us that down inside we are filled with pride. greed and selfishness. Most of all, our hearts are stubborn and rebellious against God. We may hide this; we may even claim it's not true. But the Bible's indictment is blunt: "The hearts of men, moreover, are full of evil and there is madness in their hearts while they live" (Ecclesiastes 9:3).
This is why we need Christ, because only He can forgive our sins and change our hearts from within. And He will, as we ask Jesus Christ to come into our hearts and rule every part of our lives. Don't delay, but by faith ask Christ to come into your heart, and commit your life to Him today.