1 Samuel 16:7 But the LORD said to Samuel, "Do not look at his appearance or at the height of his stature, because I have rejected him. For God does not see what man sees, for a man looks on the outward appearance, but the LORD looks on the heart."
Matthew 5:8 Blessed are the pure in heart, because they will see God.
1 John 4:12 No one has seen God at any time. If we love one another, God resides in us and his love is perfected in us.
Once I said in a Sunday school class, that one who obeys every commandment, they can still go to Hell for eternally if the Word does not travel the 18 inches between the head and the heart.
God created us because He wanted to love us, and for us to love Him back. To love God is to obey Him (John 14:15), just like the wedding vows when we marry.
One day, I drove from Nashville to Suffolk, a 700 mile journey. I listened to the entire New Testament. When I listened to the Sermon of the Mount, light bulbs appeared in my head. I thought, "Chapter five is all about the heart!" I had taken a class on Matthew, and the teacher totally missed that point. When we have superficial obedience, we will relapse over and over again because we have a heart problem.
Jesus spoke in his Sermon on the Mount about commands as "do not murder" and "do not commit adultery" and pointed out that the people back then could be angry or lustful and technically not break the murder or adultery laws. We can do and say awful things, yet obey every local, state and federal law. Jesus saw that though a system of laws alone does not change the heart. He said that He didn't want to destroy the Old Law, rather He wanted to be a fulfillment of it. He wanted to show everyone how His heart bridges the gap between keeping laws and being transformed in heart. Jesus used Himself as an example of how God wanted out the Old Testament people to become.
Those passages speak of commandments. But it also talks of causes and effect of the heart. If you don't want to murder, get the anger out of your heart. If you don't want to commit adultery or other sexual sin, get the lust out of your heart. If you don't want to hate enemies, get the hatred out of your heart.
Listen to Jesus about an empty converted heart:
Luke 11:24 "Whenever an unclean spirit has gone out of a person, it travels through waterless places searching for rest, and does not find it. It says, "I will return to my house from which I came out." 25 And when it arrives it finds the house swept and put in order. 26 Then it goes and brings along seven other spirits more evil than itself, and they go in and live there. And the last state of that person becomes worse than the first!"
This passage teaches us that it is not enough to sweep Satan out of our heart. We must fill our swept hearts with the goodness of Jesus.
Our behavior will tell others about what fills your heart.
Luke 6:45 The good person out of the good treasury of his heart brings forth good, and the evil person out of his evil treasury brings forth evil. For out of the abundance of the heart his mouth speaks.
Matthew 12:34 Offspring of vipers! How are you able to say good things when you are evil? For from the abundance of the heart the mouth speaks.
Don't just change what you say, change how you feel in your heart and what you say will change with your heart.
Here are some more passages about the heart playing the key role in the New Testament, prophesied by Jeremiah:
Jeremiah 31:33 "But this is the covenant (New Testament) that I will make with the house of Israel after those days," declares the LORD: "I will put my law in their inward parts and on their heart I will write it, and I will be to them God, and they themselves will be to me people.
Jeremiah 24:7 And I will give to them a heart to know me, that I am the LORD.
Here are more Scriptures about the heart
1 Samuel 12:24 Only fear the LORD and serve him faithfully with all of your heart. For consider what great things he has done for you. (NOTE: We love because He first loved us - 1 John 4:10)
Psalm 24:3 Who may ascend the mountain of the LORD? And who may stand in his holy place? 4 He who is innocent of hands and pure of heart,who does not lift up his soul to falseness,and does not swear deceitfully. Psalm 24:3-4
Matthew 15:8 "This people honors me with their lips, (superficial obedience) but their heart is far, far away from me."
Head knowledge is important, but our hearts will determine where we are going to spend our eternity.