Baptism is the great act by which we are drowned and drawn into the new reality of faith. Baptism is the visible mark that the new reality of God's redemption has overtaken us. God's promise has been delivered so that our trust will result in works of love. We receive and are therefore enabled to give. Our evangelical tradition teaches clearly that baptism is for the forgiveness of sin and sins.
Baptism brings the new reality.
This brings us to the second article of the creed. We believe in the forgiveness of sins only because we trust that God has ultimately dealt with our sinful condition. If baptism only dealt with particular acts of sin, we would have to be rebaptized. But that is forbidden. Having been baptized, we may trust fully that God will keep his promise to set us free.