One who interposes between two parties at variance to reconcile them; an intercessor; an intermediary agent, or go-between. In the Scriptures the term is applied to Moses and Jesus, the mediators respectively of the Law covenant and the new covenant.​—Ga 3:19; 1Ti 2:5.

Blood Required for Covenant Validation. The inspired writer of the book of Hebrews discusses two principal covenants, the Law covenant and the new covenant. In this discussion he refers to Christ’s mediating the new covenant. (Heb 9:15) His words at Hebrews 9:16 have been a subject of controversy among Bible scholars. Accordingly, the text has been rendered in the following ways: “For where a testament is, there must also of necessity be the death of the testator.” (KJ) “For where a will is involved, the death of the one who made it must be established.” (RS) “For where a covenant is it is necessary for the death to be brought in of him that hath covenanted.” (Ro) “For where there is a covenant, the death of the human covenanter needs to be furnished.” (NW) “For where a covenant is, the death of the covenant-victim to come in is necessary.” (Yg) “For where a  Covenant exists, the Death of that which has ratified it is necessary to be produced.” (ED) “For where a covenant is, there is a necessity for the death of that which establisheth the covenant.”​—The New Testament in an Improved Version.

The literal rendering as set forth in interlinear translations of the Greek text is as follows: “Where for covenant, death necessity to be borne of the one having made for self covenant.” (Heb 9:16, Int) “For where there is a covenant, the death there is necessity to be offered of the one making covenant.”​—The Interlinear Greek-English New Testament, translated by Alfred Marshall.

The rendering of di·a·theʹke as “covenant” expresses correctly the writer’s meaning. The renderings “testament” and “will,” found in many versions, are inconsistent with the use of the term in the Greek Septuagint as well as in many places in the Christian Greek Scriptures. (Lu 1:72; Ac 3:25; 7:8; Ro 9:4; 11:27; Heb 8:6-10; 12:24) “Will” and “testament” also are out of harmony with what Paul is talking about, as he is speaking of the Law covenant and the new covenant in the context. Neither the Law covenant nor the new covenant was a “will.”

At Hebrews 9:16 the apostle Paul was evidently speaking of covenants between God and man (not man and man) as requiring sacrifices. And it may be noted that, particularly with the Hebrews, approaches to God and covenants with God were regularly based on sacrifices, the victims sacrificed sometimes being cut in pieces on the occasion of entering a covenant. It is quite obvious that the Law covenant and the new covenant required the shedding of blood in order to go into operation or to be effective before God. Otherwise God would not have recognized them as valid, nor dealt with the persons involved on the basis of a covenant relationship. (Heb 9:17) For the validation of the Law covenant, the sacrifice used was that of animals​—bulls and goats—​these taking the place of Moses, the mediator. (Heb 9:19) For validating the new covenant, the sacrifice was the human life of Jesus Christ.​—Lu 22:20; see NW appendix, p. 1584.

The Mediator of the Law Covenant. Moses was the mediator of the Law covenant between Jehovah God and the nation of Israel. Jehovah spoke with him “mouth to mouth” (Nu 12:8), although actually Jehovah’s angel spoke representatively for God. (Ac 7:38; Ga 3:19; Heb 2:2) Moses was an intermediary spokesman for Jehovah to Israel. (Ex 19:3, 7, 9; 24:9-18) As mediator he was “entrusted with all [Jehovah’s] house.” (Nu 12:7) In mediating the Law covenant he helped the nation of Israel to keep the covenant and to receive its benefits.

Validation of the Law covenant. The apostle Paul says: “Now there is no mediator where only one person is concerned, but God is only one.” (Ga 3:20) In the Law covenant God was one party; the nation of Israel was the other ‘party.’ Because of their sinful condition, the Israelites were unable to approach God in a covenant. They needed a mediator. Their weakness was demonstrated in their request to Moses: “You speak with us, and let us listen; but let not God speak with us for fear we may die.” (Ex 20:19; Heb 12:18-20) Accordingly, Jehovah mercifully constituted Moses mediator of the Law covenant and arranged for animals to be sacrificed to validate the covenant. Moses, of course, was also imperfect and sinful; however, he enjoyed a favorable standing with God, even as Abraham had earlier. (Heb 11:23-28; see DECLARE RIGHTEOUS [How “counted” righteous].) On the occasion of the inauguration of the covenant, Moses officiated, directing the sacrifice of the animals. Then he sprinkled their blood on the scroll or “the book of the covenant.” He read the book to the people, setting forth the terms, and the people responded by agreeing to obey. Moses then sprinkled them (doubtless the representative older men) with the blood, saying: “Here is the blood of the covenant that Jehovah has concluded with you as respects all these words.”​—Ex 24:3-8; Heb 9:18-22.

Inauguration of the priesthood. The designated priests of the house of Aaron could not begin functioning as priests on their own. They had to be installed in office under the direction of God’s mediator Moses. When this took place, Nisan 1-7, 1512 B.C.E., Moses anointed the tabernacle and its furniture and utensils and also anointed Aaron with the oil of special composition. After filling the hands of Aaron and his sons with sacrificial materials, Moses waved their filled hands before Jehovah, thereby consecrating them or ‘filling their hands with power’ for the priesthood. Afterward he spattered them with the anointing oil and blood from the altar. So one function of Moses’ mediatorial office was the installing and setting in operation of the priesthood, which was a feature of the Law covenant.​—Le 8; Heb 7:11; see INSTALLATION.

Moses also played a significant part in connection with the first services performed by the newly installed priesthood, Nisan 8, 1512 B.C.E., as he directed the procedure and, along with Aaron, blessed the people. (Le 9) Throughout the institution of all things pertaining to the Law  covenant, he acted in his official capacity as mediator.

Other mediatorial work. A body of more than 600 laws, including the priestly statutes, was given to Israel through Moses. By the power of God, Moses performed many miracles in behalf of the people. He interceded for them, pleading with Jehovah to spare them for Jehovah’s name’s sake. (Ex 32:7-14; Nu 14:11-20; 16:20-22; 21:7; De 9:18-20, 25-29; 10:8-11) Moses had the interests of Jehovah’s name and also the people’s interest at heart even above his concern for his own welfare.​—Ex 32:30-33; Nu 11:26-29; 12:9-13.

Parallels in Mediatorships. With respect to those brought into the new covenant, we find a situation similar to that of ancient Israel. Christians are also sinners. Since the blood of animals cannot actually remove sins (Heb 10:4), a better sacrifice is necessary. Jesus Christ is that better sacrifice. (Heb 10:5-10) The writer of Hebrews expresses the matter in this way. After mentioning the sacrifices offered under the Law, he says: “How much more will the blood of the Christ . . . cleanse our consciences from dead works that we may render sacred service to the living God? So that is why he is a mediator of a new covenant, in order that, because a death has occurred for their release by ransom from the transgressions under the former covenant, the ones who have been called might receive the promise of the everlasting inheritance. For where there is a covenant, the death of the human covenanter needs to be furnished. For a covenant is valid over dead victims, since it is not in force at any time while the human covenanter is living.”​—Heb 9:11-17.

Paul goes on to point out that the former covenant was not inaugurated without blood. Moses, in negotiating it, saw that the sacrifices were made and sprinkled the blood on “the book of the covenant.” (Heb 9:18-28) Likewise Jesus Christ, God’s Mediator for the new covenant, after his sacrifice, appeared before Jehovah God with the value of his blood. Another likeness is that the Law covenant was made with a nation, not with individuals (Ex 24:7, 8), and so, too, the new covenant is made with God’s “holy nation,” “the Israel of God.”​—1Pe 2:9; Ga 6:15, 16.

Those for Whom Christ Is Mediator. The apostle Paul declares that there is “one mediator between God and men, a man, Christ Jesus, who gave himself a corresponding ransom for all”​—for both Jews and Gentiles. (1Ti 2:5, 6) He mediates the new covenant between God and those taken into the new covenant, the congregation of spiritual Israel. (Heb 8:10-13; 12:24; Eph 5:25-27) Christ became Mediator in order that the ones called “might receive the promise of the everlasting inheritance” (Heb 9:15); he assists, not the angels, but “Abraham’s seed.” (Heb 2:16) He assists those who are to be brought into the new covenant to be ‘adopted’ into Jehovah’s household of sons; these eventually will be in heaven as Christ’s brothers, becoming a part with him of the seed of Abraham. (Ro 8:15-17, 23-25; Ga 3:29) He has transmitted to them the promised holy spirit, with which spirit they are sealed and are given a token of what is to come, their heavenly inheritance. (2Co 5:5; Eph 1:13, 14) The total number of those who are finally and permanently sealed is revealed in Revelation 7:4-8 as 144,000.

Inauguration of the New Covenant. After Jesus died and was resurrected, he entered into heaven to appear before the person of God to present his offering, the benefits of which go first to those taken into the new covenant. (Heb 9:24) Here he acted both as High Priest and Mediator. In harmony with the pattern followed at the inauguration of the Law covenant, Jesus Christ presented the value of his sacrifice before God in heaven (even as Moses sprinkled the blood on the book of the Law [for God was not personally present there]). Then, on Pentecost day, 33 C.E., Jesus poured out the holy spirit from God on the first ones brought into the new covenant, about 120 persons. Later that day about 3,000, Jews and proselytes, were added to the congregation. (Ac 1:15; 2:1-47; Heb 9:19) And just as Moses read the Law to the people, so Jesus Christ clearly enunciates the terms of the new covenant and its laws to those sharing in it.​—Ex 24:3-8; Heb 1:1, 2; Joh 13:34; 15:14; 1Jo 5:1-3.

Holding the offices of Mediator and High Priest, Jesus Christ, being immortal, is always alive and able to plead for those of spiritual Israel approaching God through him, so that he can mediate the new covenant until those persons receiving his mediatorial assistance are saved completely. (Heb 7:24, 25) He is able to conduct matters to the successful completion of the new covenant. Those in the covenant are eventually installed in the heavenly priesthood as underpriests with Christ, their great High Priest.​—Re 5:9, 10; 20:6.

Blessings to Mankind in General. While Jesus’ mediatorship operates solely toward those in the new covenant, he is also God’s High Priest and the Seed of Abraham. In fulfilling his duties in these latter two positions, he will bring blessings to others of mankind, for all the nations are to be blessed by means of Abraham’s seed. Those in the new covenant are first blessed by Christ,  the primary Seed (Ga 3:16, 29), being brought in as associate members of the seed. Being made kings and priests by reason of the new covenant that he mediated, they will share in administering the blessings of Jesus’ sacrifice and of his Kingdom rule to all the nations of the earth. Christ’s mediatorship, having accomplished its purpose by bringing “the Israel of God” into this position, thus results in benefits and blessings to all mankind.​—Ga 6:16; Ge 22:17, 18.

There are, thus, others not of the 144,000 “sealed” ones who also pray to Jehovah God in the name of Christ, putting faith in the merit of his ransom sacrifice. This sacrifice is not only for those for whom Jesus mediates the new covenant but also for all mankind expressing faith in Christ. (1Jo 2:2) These not in the new covenant also appreciate that “there is not another name under heaven that has been given among men by which we must get saved.” (Ac 4:12) They, too, look to Jesus Christ as their great heavenly High Priest, through whom they can approach God and through whose ministration they can get forgiveness of sin. (Heb 4:14-16) Revelation 21:22-24 points out that ‘the nations will walk in the light of New Jerusalem,’ where Jehovah God is the light and the Lamb Jesus Christ is the lamp.