"YOU were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and in the Spirit of our God." One must appreciate the magnitude of the gift God has given us in the sacraments of Christian initiation in order to grasp the degree to which sin is excluded for him who has "put on Christ." But the apostle John also says: "If we say we have no sin, we deceive ourselves, and the truth is not in us." and the Lord himself taught us to pray: "Forgive us our trespasses," linking our forgiveness of one another's offenses to the forgiveness of our sins that God will grant us.
Source: Catechism of the Catholic Church (Vatican.va)