“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. (1 Ti 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 spiritual 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.”—Insight on the Scriptures, Vol. 2, page 362.
The publication, "Worldwide Security Under the 'Prince of Peace'" on pp. 10-11 says,
"Likewise, the Greater Moses, Jesus Christ, is not the Mediator between Jehovah God and all mankind. He is the Mediator between his heavenly Father, Jehovah God, and the nation of spiritual Israel, which is limited to only 144,000 members."
And the Watchtower from 1979 April 1 p.31 concurs,
"Is Jesus the "mediator" only for anointed Christians? … So in this strict Biblical sense Jesus is the "mediator" only for anointed Christians. …The "great crowd" of "other sheep" that is forming today is not in that new covenant. However, by their associating with the "little flock" of those yet in that covenant they come under benefits that flow from that new covenant."
The quotations above officially excludes millions of Jehovah’s Witnesses from true reconciliation with God. Hebrews is the only letter in the New Testament that explains Jesus’ priesthood and it specifically limits it to those in the New Covenant.
"But because He remains forever, He holds His priesthood permanently. Therefore He is able to save completely those who come to God through Him, since He always lives to intercede for them. For this is the kind of high priest we need: holy, innocent, undefiled, separated from sinners, and exalted above the heavens. - Hebrews 7:24-26 HCSB
Now the Messiah has appeared, high priest of the good things that have come. In the greater and more perfect tabernacle not made with hands (that is, not of this creation ), He entered the holy of holies once for all, not by the blood of goats and calves, but by His own blood, having obtained eternal redemption. - Hebrews 9:11-12 HCSB
“For it is clear that He does not reach out to help angels, but to help Abraham’s offspring. Therefore, He had to be like His brothers in every way, so that He could become a merciful and faithful high priest in service to God, to make propitiation for the sins of the people.”—Heb. 2:16,17 HCSB
Why is this important? It is because of the nature of the Gospel and the nature of propitiation. Propitiation is the removal of God's wrath. "For God's wrath is revealed from heaven against all godlessness and unrighteousness of people who by their unrighteousness suppress the truth." (Romans 1:18 HCSB) "They are justified freely by His grace through the redemption that is in Christ Jesus. God presented Him as a propitiation through faith in His blood." (Romans 3:24-25a HCSB) "For this is My blood that establishes the covenant; it is shed for many for the forgiveness of sin." (Matthew 26:28 HCSB) Jesus' death is the sin offering that turns away God's wrath and forgives the sins of those in the New Covenant. If you are not in the New Covenant, you are in covenant with Adam, and thus under the Wrath of God. "For just as in Adam all die, so also in Christ all will be made alive." (1 Corinthians 15:22 HCSB, compare with Romans 5:12-21)
Ask the next Witness who calls on you who is his mediator? If he says Jesus Christ, ask him if he is in the New Covenant? If is not in the New Covenant what covenant relationship is he in other then the Prelaspsarian Ademic Covenant? The vast majority of Witnesses are even forbidden from taking communion. They have no part theologically and practically in the body and blood of Christ. They have no basis to claim to be sons of God or the children of Abraham. So, they don't have Jesus Christ as the mediator between themselves and a Holy God because they are told they are not in the New Covenant. They have not experienced the new birth, and are thus dead in their sins (Eph. 2:1-9). They can't claim to be saints, and thus much of the New Testament isn't even written to them or for them. Does the witness at your door view himself as a son of God? If he is not a son, how can he speak of Jehovah God as his Father? Is he led by God’s spirit? If so, how can he deny being a sons of God when the apostle Paul said “All those led by God’s Spirit are God’s sons.”—Romans 8:14 HCSB
What the Watchtower teaches here is demonic. It denies people the only way that they can be saved, that is through the Gospel. The Gospel is that "God will credit righteousness—for us who believe in him who raised Jesus our Lord from the dead. He was delivered over to death for our sins and was raised to life for our justification." (Romans 4:24-25 NIV) They claim that you do not have to have Christ as your mediator to be saved. But the words of Christ the Lord are crystal clear: "So Jesus said to them, 'I assure you: Unless you eat the flesh of the Son of Man and drink His blood, you do not have life in yourselves. Anyone who eats My flesh and drinks My blood has eternal life, and I will raise him up on the last day,'"(John 6:53-54 HCSB)
If you are a Jehovah's Witness, please hear me: You don't need the Watchtower or the "Faithful Slave", you need JESUS and the forgiveness of sins he offers in the New Covenant. Outside of that, you have no hope.