How much was the ransom? God’s justice did not require an exact equivalent man-for-man sacrifice between the First Adam and Jesus, the Second Adam. God’s gift required more.
Reducing Jesus Christ to a mere man and nothing more is, among other things, essential to the Jehovah's Witnesses’ religious philosophy. They do this in part by arguing that God’s law requires a strictly equivalent human ransom (Jesus) to compensate for Adam’s sin of disobedience, restore the balance and reinstate the right to perfect human life on earth. Their rationale, however, is flawed for numerous reasons. The Jehovah's Witnesses write:
One of the main reasons why Jesus came to earth also has a direct bearing on the Trinity. The Bible states: “There is one God, and one mediator between God and men, a man, Christ Jesus, who gave himself a corresponding ransom for all” (1 Timothy 2:5,6).
Jesus, no more and no less than a perfect human, became a ransom that compensated exactly for what Adam lost - the right to perfect human life on earth. So Jesus could rightly be called “the last Adam” by the apostle Paul, who said in the same context: “Just as in Adam all are dying, so also in the Christ all will be made alive.” (1 Corinthians 15:22, 45) The perfect human life of Jesus was the “corresponding ransom” required by divine justice - no more, no less. A basic principle even of human justice is that the price paid should fit the wrong committed.
If Jesus, however, were part of a Godhead, the ransom price would have been infinitely higher than what God’s own law required. (Exodus 21:23-25; Leviticus 24:19-21) It was only a perfect human, Adam, who sinned in Eden, not God. So the ransom, to be truly in line with God’s justice, had to be strictly an equivalent - a perfect human, “the last Adam.” (Should You Believe, Chapter 6)
The Jehovah's Witnesses are greatly mistaken. First, a literal translation of 1 Timothy 2:6 states that Christ Jesus gave “…Himself a ransom on behalf of all” (Green's Literal Translation, NAB, RSV). There is no mention that this ransom was “corresponding” and the Jehovah's Witnesses’ insertion of this word leaves an improper impression of exact equivalency - one human for another mirrored human, no more.
Secondly, the Jehovah's Witnesses erroneously teach that God’s justice necessitates an exact human-for-human match, quoting Exodus 21:23-25 and Leviticus 24:19-21, the old Mosaic Law, a pre-Christian standard of justice requiring an eye for an eye and a tooth for a tooth as just punishment. But Christians are not subject to the Mosaic Law, and the Jehovah‘s Witnesses know this. Jesus nailed the Law to the cross and specifically rejected this “eye for an eye” standard of justice at Matthew 5:38, 39:
You have heard that it was said, ‘an eye for an eye and a tooth for a tooth.’ But I say to you, Do not resist one who is evil. But if any one strikes you on the right cheek, turn to him the other also;…
Third, the Jehovah's Witnesses’ underlying premise that one of Christ’s purposes was to redeem man and provide a conditional right to perfect human life on earth is flawed in ways too numerous to list here. The idea that mankind’s destiny is to return to a condition of naked semi-tropical bliss and ignorance in Gardens of Eden (a return to the status quo) where they will be ruled by the anointed 144,000 from heaven defies reason and Scripture. These issues, in particular the false theory that redeemed man will be ruled on earth by a heavenly class of 144,000, are exhaustively addressed in the accompanying treaties entitled ‘Why the Jehovah's Witnesses are Wrong in Teaching that only 144,000 go to Heaven to Rule over Humans on earth.’
Fourth, the condition of redeemed mankind shall be nothing like the condition that Adam and Eve experienced because they were not immortal and were always subject to death as a consequence of disobedience. By virtue of Christ’s sacrifice, however, death is done away with for the saved, “Death is swallowed up in victory” (1 Corinthians 15:54, 55); Christ abolished death (2 Timothy 1:10). The end result is a “new creation,” as all things are ultimately made new (Revelation 21:5), including the resurrected glorified human body of the believer which shall resemble Christ’s resurrected body (Philippians 3:20, 21), a body which is not the same as Adam’s mortal fleshly body.
The “gift is not like the transgression but much more” (Romans 5:15 NAB). “God’s grace in Christ will yet accomplish more than what Adam lost” (Strong and Vines, 77), whereas the ransom death of a mere man would be insufficient to attain the higher reward.
But our commonwealth is in heaven, and from it we await a savior, the Lord Jesus Christ, who will change our lowly body to be like his glorious body, by the power which enables him even to subject all things to himself. (Philippians 3:20, 21)
Fifth, the very idea that Christ was, and is, nothing more than a man, the equivalent of Adam, as the Jehovah's Witnesses falsely teach, ignores the divine Person of Jesus of the Bible, and His many miracles, displays of power and all that Jesus said about himself. His ransom sacrifice was not an exact equivalent on par with Adam; it was not even close. The sacrifice was exceedingly greater.
Sixth, Man alone cannot redeem himself. To share in divinity and immortality requires the intercession of the divine, the God-man, Jesus, as Athanasius taught.
Christ came and freely took upon Himself the penalty of sin - death and suffering - and by so doing He made satisfaction for the sin of man. Being God and man, He could do what only God can do: have a hold on and restore the whole of human nature and race. (No single merely human individual could do so.; if Adam could so act for the worse, it was because he happened to be the head of the race).(Catholic Encyclopedia, 931)
The fact that a mere man, Adam, brought down mankind in a single act of disobedience by eating a piece of fruit does not mean a mere man (the Jehovah’s Witnesses’ Jesus) could restore the human race to God’s good graces and enable man to attain immortality and much more. Put another way, just because you chop down a tree doesn’t mean you can make it grow.