The word "heart" means:
Personality, inner life or character
Seat of emotions like joy or sorrow, courage and fear
Intellectual activities: reflection, memory, understanding
Volition or purpose: the will
Why? Because of corruption or sinfulness.
Genesis records that God searched human hearts and found much evil.
"And GOD saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually."
Genesis 6:5
Why? Because people keep breaking themselves
on God's moral laws.
The physical law of gravity is not broken when I jump off the rooftop. Instead, I am broken. God's prophets, like Jeremiah, spoke of the day when God's moral law would find a natural place in our hearts
and we would recover from our brokeness.
"I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. And they shall teach no more every man his neighbor, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more."
Jeremiah 31:33-34
Why? Because we are blinded to the ways of God and can't experience spiritual life.
Jesus was very upset over the spiritual ignorance of people.
He promised spiritual healing.
"For this people's heart has grown dull,
and their ears are heavy of hearing,
and their eyes they have closed,
lest they should perceive with their eyes,
and hear with their ears,
and understand with their heart,
and turn for me to heal them.'
But blessed are your eyes, for they see, and your ears, for they hear."
Matthew 13:15
The key to life is a change of heart.
That change starts with our personal confession that Jesus is Lord. New life is the result of Christ's Spirit working within our believing heart to radically heal us and help us become a new person.
"The word is near you, on your lips and in your heart (that is, the word of faith which we preach); because, if you confess with your lips that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved. For man believes with his heart and so is justified, and he confesses with his lips and so is saved."
Romans 10:8-10
"Lord Jesus, I believe you can change my heart. I confess my need for healing and your ability to heal my broken heart.
Renew my heart and give me your Spirit
that I might live for you. Amen"