Is Baptism the Sign of the New Covenant?

Let me start by saying that I have no theological axe to grind on this issue, and I am not trying to protect or attack any particular doctrinal view in raising this question. I am simply trying to think and speak more biblically about the ordinances of baptism and the Lord’s Supper.

With that said, my question is this: Is baptism the sign of the New Covenant? This seems to be the common assumption, but I think it is an assumption worth challenging. As I have begun to wrestle with this—and I am only now in the beginning stages—I have come to four conclusions:

First, the Bible does not use the word “sign” in connection with the New Covenant. The two candidates for the sign of the New Covenant would seem to be water baptism and the Lord’s Supper. But since neither one is explicitly referred to as the “sign” of the New Covenant, it is difficult to be dogmatic one way or the other.

Second, there is clear biblical data which seems to suggest that the Lord’s Supper is the sign of the New Covenant. At the Last Supper, when Jesus held up the bread and said to His disciples, “This is My body” (Luke 22:19), He meant that it symbolically represented or signified His body. Likewise, when He held up the cup and said “This cup…is the New Covenant” (Luke 22:20), He meant that it symbolically represented or signified the New Covenant. Therefore, as that which signifies the New Covenant, the Lord’s Supper at least appears to be the sign of the New Covenant.

Third, although baptism does symbolize the forgiveness of sins (Acts 22:16)—which is one of the key promises of the New Covenant—it is never explicitly connected to the New Covenant itself in the way that the Lord’s Supper is.

Fourth, the Lord’s Supper seems to be a more likely candidate for the sign of the New Covenant because believers celebrate it regularly—perhaps even weekly (1 Cor 11:23-26; Acts 2:42, 46; 20:7)—in contrast to how believers are baptized only once. This regular reminder seems to fit better with the pattern of the previous covenant signs which served as recurring reminders of their respective covenants: a rainbow periodically appears in the sky as a reminder of the Noahic Covenant (Gen 9:8-17); circumcision (or at least its effects) provided a regular reminder of the Abrahamic Covenant to the one who had been circumcised (Gen 17:10-14); and the Sabbath provided a weekly reminder of the Mosaic Covenant (Exod 31:12-17). In contrast, an individual is baptized just once, and when the ordinance has been completed, there is no recurring reminder (other than the baptism of other individuals).

Therefore, if there is but one sign of the New Covenant, and if that sign is the Lord’s Supper, then it would seem unbiblical to refer to baptism as the sign of the New Covenant. Two concluding questions:

1. Where is the breakdown in this argument?
2. If baptism is not “the sign of the New Covenant,” how exactly should we think of it and refer to it? In other words, precisely what relationship does baptism have to the New Covenant?