Do you ever think about what a wedding ring means? Giving and receiving the ring doesn't make one married. But it does two things: it is a sign/symbol of marriage and it is a pledge of martial faithfulness to each  other. That is also true of the sacraments of the church. We'll look at the sacraments as a whole, but referring more specifically through the lens of an Old Testament sacrament which Paul cites in Romans 4: circumcision.
Scripture: Romans 3:21 - 4:12