Blush --
It was an epiphany for me when I realized that the ordinances of the Old Covenant worked "ex opere operato", that is, they did what they symbolized. When the flesh of the man was cut off in circumcision, then at the same time, he was also cut off from the pagan lands around him and made one of God's peculiar people. In other words, the physical and seen action of cutting did the spiritual work of separation. What was seen in the physical world actually happened in the spiritual world.
Also, every circumcision was an outward and visible testimony of the Messias who was promised to the world. It was a prophecy of a MALE, whose flesh would be CUT OFF for the sins of the world, and who would BLEED to establish the New Covenant.
In like manner, in the New Covenant, we also have Sacraments which use PHYSICAL OBJECTS to achieve spiritual results. As I posted above, when we are dipped in the deep water (yes, sir!! I am a "deep water" person!!!) we picture that which Romans 6: 3 says is really happening, i.e. we are dying and being buried with Christ and being raised to new life in Him. The physical and seen testifies to the reality of the spiritual and unseen.
And baptism also testifies to the Messiaship of Jesus the Christ, for every time we are baptized, we proclaim his death, burial, and resurrection of this Jesus as payment for the sins of the world. That is why circumcision had to be changed to baptism -- to circumcize (in a religious context as the Jews still do) is to DENY that Jesus is the Christ, God's Son and Savior of the world. There had to be a new covenantal sign/seal which operated just like the old one in both speaking of the Messias as well as working "ex opere operato".
It simply cannot be the waters of birth (as some Protestants claim) or anything else. Covenantal theology will not allow for it.
Cordially in Christ,
Brother Ed