…through this man forgiveness of sins is proclaimed to you, and by him everyone who believes is freed from everything from which you could not be freed by the law of Moses.
They were freed from everything they couldn’t find freedom from before. The blood of bulls couldn’t free them from sin. The blood of Jesus gives us forgiveness, but the bull afforded them that. Now we are free from sin. Being baptized with the Holy Spirit gives us power to overcome sin, and we become slaves of righteousness, free from the power of sin.
Our given task isn’t evangelism. The Great Commission is to baptize them and teach them to keep all Christ’s commands. Preaching the forgiveness of sins doesn’t fulfill our mission. We need baptism, which is the cutting off of the old man, our identifying by faith with Christ in His death and burial, and our raising with Him to new life, by faith identifying with His resurrection and receiving His life by the Spirit. In the Bible there was no prayer of salvation; there was baptism. That’s just day one. Then we follow Jesus on the paths of righteousness. Our given mission is to teach them to keep Christ’s commands. They need to know and obey them.