Sinners (and that’s what we are) are incapable of approaching a Holy God directly. We need a mediator, a stand-between, a reconciler, an advocate who will represent us before God, and take our place, and bear our sin, and render us acceptable to God, and bring us into God’s presence with joy.
In the Old Testament human priests and sacrifices symbolically fulfilled this function, but Jesus Christ is the only real mediator for the people of God. It is he who has paid the penalty for our sins and opened the way to God. Though human priests are no longer necessary for true worship, Jesus mediation is absolutely essential. Through him, and him alone, we can approach God with confidence. As the Westminster Divines reminds us “Religious worship is to be given to God, the Father, Son, and Holy Ghost; and to him alone; not to angels, saints, or any other creature: and, since the fall, not without a Mediator; nor in the mediation of any other but of Christ alone” (Westminster Confession of Faith, 21.2).
Thus, everything in our public services ought to confirm that we believe with all our hearts that we understand that “it is impossible for the blood of bulls and goats to take away sins,” (Heb 10:4) “But when Christ had offered for all time a single sacrifice for sins, he sat down at the right hand of God, . . . For by a single offering he has perfected for all time those who are being sanctified,” (Heb 10:12-14) and “Therefore, brothers, since we have confidence to enter the holy places by the blood of Jesus, by the new and living way that he opened for us through the curtain, that is, through his flesh, and since we have a great priest over the house of God” (Heb 10:19-21). As Protestants, we have no priest but Jesus, no mediator but the only redeemer of God’s elect. He has done everything necessary to bring us to God, and we come to God only through him. Nothing we do in our public ought to give the impression that Jesus’ mediation needs to be improved or supplemented (or that it may be supplanted or is unnecessary) and everything we do ought to witness to our joy in the glory of his sole mediation.
This truth is deeply reflected in historic Reformed practices regarding the observance of the Lord’s Supper. For instance, the truth of Jesus’ sole mediation is one reason the Presbyterian ministers stand behind the communion table (and not in front of it) when the Lord’s Supper is administered. We do not mediate between God and his people. We are instruments not mediators. We are pastors not priests. The people of God do not come to Jesus through us, rather Jesus’s administers his call to table fellowship through us directly to his people, and they come to him. Thus the Lord’s Supper is a meal, and he is the host and mediator. His ministers are but servants and stewards, announcing in his own words his invitation to repentant sinners, burdened saints to come, by the aid of the Holy Spirit, to come “take, eat, drink” and sup with the risen, ascended, enfleshed Lord at the right hand of his Father, by faith. This is, by the way, something that has been forgotten in the unintended symbolism of some of the diversity of communion practices in many of the Reformed churches today.