1Mk 16:15; ²Mt 28:19–20; ³1 Cor 11:23–25; ⁴2 Cor 3:6–18; Heb 8:6, 10–11; Mt 28:19

When we speak about the administration of the Covenant of Grace, we are talking about how Christ, the mediator of the covenant and the benefits of the covenant purchased by Him is administered or displayed and applied to members of the covenant.

This Covenant of Grace, though made in eternity was revealed to man and took effect immediately after the Fall. Under the Old Testament, it was administered in "promises, prophecies, sacrifices, circumcision, the passover, and other types and ordinances, which did all fore-signify Christ then to come" (WLC 34).

The essence of the covenant remains the same under the New Testament. But Christ who is the substance or reality pointed to by the Old Testament shadows has come. Therefore the promises and prophecies have been, and are being fulfilled; the sacrifices and ordinances found their antitypes (fulfilment) and the bloody sacraments can no longer retain their forms (as the blood of Christ has been shed).

Under the Old Testament, the Covenant was administered through a complex of ordinances and rites, which appealed to senses of sight (e.g. watching the sacrifice of animals), of hearing (e.g. of trumpets and musical instruments), of taste (e.g. of bitter herbs) and of smell (e.g. of the perfume or anointing oil). The Old Testament saints were,—spiritually considered,— children, and God taught them in much the same way as we would teach children: by appealing to the senses. Under the New Testament, the saints have,—spiritually speaking,—grown up, and God appointed for them fewer, simpler, and more decidedly spiritual forms of worship. This change was spoken of by the Lord to the Samaritan woman:

The New Testament administration of the Covenant of Grace (which is part of New Testament worship), may be reduced to three things: the preaching of the Word, baptism and the Lord’s Supper.

Firstly, it is administered by preaching of the Word. Although the Word was preached even during Old Testament times, preaching was never given as much prominence as the other things that appealed to the senses. Our Lord moreover appointed preaching, as a means to gather and strengthen the elect sheep from all over the world. This is why the Lord charged His disciples: "Go ye into all the world, and preach the gospel to every creature" (Mk 16:15).

Secondly, the Covenant of Grace under the New Testament is also administered with baptism, which is the bloodless replacement of circumcision, as a sign and seal of the covenant by which particularly, the benefits of the covenant such as regeneration, and forgiveness of sin is exhibited and applied.

Thirdly, the Covenant of Grace is administered with the Lord Supper, which is the bloodless equivalent of the Passover. The Lord’s Supper serves as a sign and seal of the covenant by which the death of Christ is exhibited and worthy receivers are by faith made partakers of benefits of the covenant that pertains to our sanctification.

These three means of administration of the covenant are, moreover, in a sense more effectual to the members of the covenant. Certainly the Old Testament ordinances were effectual to those who used them by faith in the Old Covenant, but the New Testament ordinances are more effectual because "grace and salvation are held forth in more fullness, evidence, and efficacy."

This fact is highlighted by the writer to the Hebrews (quoting Jeremiah to support his assertion):

While the Old Testament saints worshipped the LORD and experienced his blessings through the Messiah-Mediator, they knew Him and His work (which he would do) only in part and in a rather indistinct way. New Testament saints on the other hand, have the privilege of hindsight as well as more intricate theological explanations which were provided by the Holy Spirit through inspiration and illumination.

New Testament worshippers, as such, must never return to Old Testament forms of worship. To do so would be, not only to return to ‘childish’ ways, but to deny the Lord whom the Old Testament ordinances were pointing to, and to act as if He never came, and never rose as the Sun of Righteousness to displace all the old shadows. W