While the passage just quoted gives us a clear promise of forgiveness, many people fail to understand that it is only through personal faith in Christ that we receive what is promised (Galatians 3:22). Instead, the tendency of the human heart is either to assume that forgiveness comes automatically, simply because a rite is performed, or to explain away what is said.
One difficulty that people have in understanding baptism lies in the carnal assumption that it is some sort of work. In fact, I have met people who insist that it is a work. Yet the person who is being baptized does nothing! Moreover, the rite is designed to make it clear that salvation does not come to us through something we do, but through something that we receive from Christ. That is why self-baptism is never valid.
To come to baptism "in the name of Jesus Christ for the remission of sins," is to come believing that there is forgiveness in Christ (Acts 2:38). Christ's representative then washes you with water as a way of telling you that you now have forgiveness in Christ. However, the key factor is not immersion, but your faith that you have forgiveness in Christ. Therefore, while God uses the ceremony to give us His promise of forgiveness in Christ, it is only through personal faith in Christ that we receive what is promised (2Corinthians 1:20, Galatians 3:22).
Since the act of presenting oneself for baptism should go hand in hand with repentance, it can be seen as both, an acknowledgement of sin and a request for forgiveness (Acts 2:38). In other words, when Peter called upon his listeners to "repent and be baptized... for the remission of sins," their response was an implied request for forgiveness (Acts 2:38 and 22:16). However, that forgiveness does not come because we ask but because Christ died to secure it for us. That is why, only those who trust in him receive what is promised (Romans 5:2).
While children should be led to see their sin and look to Christ for forgiveness at the earliest possible age, we should never assume that the outward act of baptism will save them, apart from personal faith in Jesus Christ.
All who partake of the Lord's Supper receive Christ's promise that His body was given for them, and His blood "shed" for them, for the remission of sins (1 Corinthians 11:24, Luke 22:19,20, Matthew 26:26-28). However, the Bible makes it clear that it is only through personal faith in Christ that we receive what is promised (Galatians 3:22, 2Corinthians 1:20). Therefore, while the promise of Christ's body and blood is given to all that partake, only those who acknowledge their sin, looking to Christ for forgiveness, are worthy to partake (1Corinthians 11:31).
If Christ is the door to eternal life, then the gospel is the key that opens that door, for it is only through the gospel that we are brought to a saving knowledge of Jesus Christ. Therefore, when Jesus said to Peter, “I will give unto thee the keys of the kingdom of heaven” He was telling Peter that He would give him the knowledge that opens the door to eternal life, and that knowledge belongs to all who trust in Christ (Matthew 16:19). Consequently, everyone who understands the way of salvation has the keys to the kingdom of heaven, and we use those keys every time we proclaim the gospel (Matthew 18:18, John 20:21-23).
When we look at how Jesus used those keys when he was on earth, we find that He never used self-exalting language. He never said, "I, by the authority vested in me, forgive you all your sin." Instead, he simply said, "be of good cheer; thy sins be forgiven thee" (Matthew 9:2, Luke 7:48). Therefore, if we follow His example, we will be using the keys of the kingdom every time we tell someone that there is forgiveness in Christ, and all who believe that message will receive eternal life.
In order to rightly-divide the word of truth; the warnings of law must be directed at the unrepentant, while those who repent are assured of forgiveness in Christ. To that end, we are to bind sin by withholding baptism from the unrepentant, and lose sin by extending God's promise of forgiveness in Christ to those who repent. The same holds true for the lord's supper. And when we carry out this task as God intended, God works through us to forgive the sins of all who believe (John 20:23, Luke 10:16).