So, then, what kind of sacrifice could cover Adam’s sin so that Jehovah could forgive people and ‘remember their sins no more’?

An equal exchange is required​—‘soul for soul,’ that is, life for life. (Deuteronomy 19:21) Nothing less than a perfect human life​—like Adam’s life before he sinned—​could balance the scales of justice. Only someone with such a perfect life, uncontaminated by sin inherited from Adam, could provide the atoning sacrifice. (Psalm 49:7-9 [49:8-10, TNK]) Only God could produce such a perfect life, without a human father, as He did when he created Adam.​—Genesis 2:7.

Who alone could present himself as an atoning sacrifice?

Only the Messiah could be the atoning sacrifice. He will indeed come as a Deliverer. (Genesis 3:15; Psalm 2:2, 8) But first, he must provide a perfect “guilt offering”​—a complete covering for our sins, both inherited and committed.​—Leviticus 7:1; Isaiah 53:6, 10.

Why would the Messiah have to die?

Isaiah foretold that the Messiah would be rejected, “severed from the land of the living ones,” and his life would serve “as a guilt offering.” He would “bring a righteous standing to many people; and their errors he himself [would] bear.” (Isaiah 52:13–53:12; Leviticus 7:1) He would provide the sacrifice “to finish off sin, and to make atonement for error.”​—Daniel 9:24.