Our redemption by Jesus Christ began with His Incarnation. In assuming human nature, Christ deified it. By uniting the separated natures – Divine and human – in one Person, He overcame the barrier of nature that separated man from God. This was in order for Christ’s true followers to be deified: not by nature and Sonship, as Christ was, but by Grace and adoption.
But with Christ’s Incarnation, other barriers between man and God still remained. Because of his spiritual corruption, man was an impure vessel. Because of the barrier of sin, man could not receive and keep the Grace of God within himself. So Christ, having overcome the barrier of nature at His Incarnation, now had to break down the barrier of sin. He would do this through His death. As St. Nicholas Cabasilas says, Christ broke down the three barriers that separated man from God: the barrier of nature by His Incarnation, the barrier of sin by His death, and the barrier of death by His Resurrection (St. Nicholas Cabasilas, The Life in Christ, pp. 105-106).—3RD ED.
Christ’s Incarnation, death and Resurrection, which He accomplished for the salvation of mankind, expressed God’s truth, righteousness and justice on the one hand, and His mercy and love on the other. St. Gregory Palamas says the following concerning Divine justice: “The pre-eternal, uncircumscribed and almighty Word and omnipotent Son of God could clearly have saved man from mortality and servitude to the devil without Himself becoming man… But the Incarnation of the Word of God was the method of deliverance most in keeping with our nature and weakness, and most appropriate for Him Who carried it out, for this method had justice on its side, and God does not act without justice. As the Psalmist and Prophet says, God is righteous and loveth righteousness (Ps. 10:7), and there is no unrighteousness in him (91:15)” (Homilies, vol. 1, p. 179).