Read: Romans 4:1 – 12
The sacraments are visible signs and seals of the invisible grace of God to us in Christ Jesus. The sign does not by some mysterious change become the reality. It always remains only a sign. However, those who receive this God-ordained sign by faith are also blessed by the reality to which it points. The sign of baptism, which is the water of baptism, does not at any stage become the reality of the blood of Christ.
During the time of Jesus, some of the false teachers of the Jews committed the error of boasting in the mere sign of circumcision. The Scribes and the Pharisees, as they were called, boasted in the Old Testament covenant sign of circumcision. Because they were circumcised, they imagined themselves to have a special standing with God. They boasted among themselves “we be the circumcised.” They imagined that those who were not circumcised could not be in the same spiritual class as they were. In fact, many of them thought that without circumcision no one could be saved.
Against this error, the Word of God teaches that circumcision is nothing, neither is uncircumcision, but a new heart is everything. “For he is not a Jew, which is one outwardly; neither is that circumcision, which is outward in the flesh: but he is a Jew, which is one inwardly; and circumcision is that of the heart, in the spirit, and not in the letter; whose praise is not of men, but of God” Rom 2:28 - 29. In the next chapter of Romans, the same apostle speaks these words, “Seeing it is one God, which shall justify the circumcision by faith, and the uncircumcision through faith.” Rom 3:30.
The Bible does indeed sometimes speak of the reality of baptism using the wording of the sign. So people in the New Testament time, when they came to repentance and faith in Jesus Christ, were exhorted to be baptized and washed of their sins. See Acts 22:16. There is a resemblance between the sign and the thing which it signifies. As water washes away the filth of our bodies, so the blood of Christ washes away our sins. However, this does not mean that the mere rite of baptism itself could wash away sins.
When believers receive baptism by faith, they may be assured of its blessed reality of the washing away of all their sins, being incorporated into the body of Christ and receiving all the blessings of salvation in Him.
There have also been those who wrongly place their confidence in their outward baptism, and afterwards were careless about Christian living. Yet, somehow they imagine that they have standing with God just because they were baptized at some point in their lives. Some even go so far as to falsely imagine that because they were baptized, they will be saved even though they live a life of impenitent ungodliness.
There will indeed be those who received the sign of baptism, but nevertheless go eternally lost. Our concern must be that we have the spiritual reality which baptism signifies, namely the forgiveness of sins through the cross of Jesus Christ, and the new heart which the Spirit of Jesus Christ alone can and does give us.
When we know that we have these spiritual realities through lively faith in our hearts, we have continual comfort and assurance in our baptism. Furthermore, the spiritual reality of our baptism will be both the power and the incentive for serious Christian living. The spiritual reality of baptism requires daily repentance. Then, our boasting will not be in ourselves but in God only.