What are the parts of a sacrament?

The parts of a sacrament are two; the one an outward and sensible sign, used according to Christ’s own appointment; the other an inward and spiritual grace thereby signified.[1]

1. Matt. 3:11

   I baptize you with water for repentance, but he who is coming after me is mightier than I, whose sandals I am not worthy to carry. He will baptize you with the Holy Spirit and fire.

   I Peter 3:21

   Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ….

   Rom. 2:28-29

   For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. His praise is not from man but from God.

Question 163, Westminster Larger Catechism