We may receive forgiveness of our sins because Jesus Christ has redeemed us. Eph 1:7 KJV "In whom we have redemption through his blood, the forgiveness of sins." This is somewhat murky, and is better explained in NIV, "In him we have redemption through his blood, the forgiveness of sins." It is best explained in the NLT "He is so rich in kindness that he purchased our freedom through the blood of his Son, and our sins are forgiven." Redemption was well understood in the Greco-Roman culture of Jesus' day: slaves were freed by the payment of a ransom. The ransom necessary to free sinners from the bondage of sin is the blood of Jesus Christ. Redemption is translated from the Greek, apolytrosin, meaning to "release from a captive position." The death of Jesus Christ was a sacrificial death that provides relief from the captivity of sin. We receive forgiveness of sins when we acknowledge that we have sinned, repent, and trust in Jesus' atoning sacrifice. Don't be self-righteous, like the Pharisees, who believed they were not sinners. If you believe that you have no sin, you have sin, indeed.