Faith is a sovereignly granted gift, something which cannot be evoked from a man's own will. That gift of faith is an endowment, a distinguishing feature possessed by God, and inherited by those He has chosen out of the world. A peace offering; an olive branch, to facilitate repentance in His adopted children.
Along with reconciliation and restoration, repentance is a predominant theme in the relationship between God and His people. What use is faith, if it doesn't oil the wheels of change in you?
Faith, forgiveness, and spiritual renewal. Faith comes from God, so those who have faith will put on the new self, in the image of Him.
Faith is the means of entry for His Spirit to conform us to the image of His Son. To be in harmony with God, necessitates that those who abide in Him, follow in Christ's steps. Jesus had faith and did no sin, so to become like He was in the world, we must have faith and repent of sins we did in our own ignorance and pride.
Those who repent are not working for salvation, they're conveying thanks for the mercy and forgiveness which God has afforded them. A forgiveness so inexpressible to the human mind, that only the life; suffering, crucifixion, and resurrection of Jesus could convey it.