Circumcision is not a covenantal oath, but a type of regeneration. As the Passover was a type of the cross, and not of communion, so also circumcision was a type of regeneration, and not of water baptism. Baptism is a symbol, not of physical circumcision, but of the resurrection power of Jesus. We need to insist on the difference. Physical circumcision kept ALL those associated with Abraham separate from other families.
Water baptism is a symbolic separation of the regenerate from their family of generation.
Physical circumcision symbolized a possible regeneration, but was a command given with no promise of regeneration. Water baptism, on the other hand, is commanded of those who appeal to God for the good conscience which comes after the resurrection power of Jesus has done its work. Paedobaptists tend to assume that it is impossible at the same time to fulfill a covenant and to do away with it. But Jesus was BOTH physically circumcised AND also water baptized. The old was fulfilled but it was succeeded by a new covenant.