Heart faith saves and then salvation produces intellectual faith that can be renewed and transformed to do the perfect will of God.
Romans 12:2 And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God.
Romans 10:9 That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe IN THINE HEART that God hath raised him from the dead, thou shalt be saved.
There are only a few inches between the head and the heart, but heart faith takes men to Heaven and head faith dooms men to Hell.
Jeremiah 17:9 The heart is deceitful above all things, and desperately wicked: who can know it?
Matthew 5:8 Blessed are the pure in heart: for they shall see God.
Psalms 51:10 Create in me a clean heart, O God; and renew a right spirit within me.
Acts 15:8 And God, which knoweth the hearts, bare them witness, giving them (the Gentiles) the Holy Ghost, even as he did unto us; (the Jews) 9 And put no difference between us and them, purifying their hearts by faith.
Only God who created them in the first place could cleanse and purify our sinful hearts. We mortal men cannot do that.
Ephesians 3:17 That Christ may dwell in your hearts by faith;
When we receive Jesus Christ into our hearts, He cleanses and purifies them from the inside out. Then and only then we can we have pure hearts and be transformed by the renewing of our minds.
1 Timothy 1:5 Now the end of the commandment is charity out of a pure heart, and of a good conscience, and of faith unfeigned:
2 Timothy 2:22 Flee also youthful lusts: but follow righteousness, faith, charity, peace, with them that call on the Lord out of a pure heart.