From my catechism:
<Q: How does the Lord Jesus Christ accomplish our salvation?
>A: The Son of God accomplished our salvation by His incarnation, His teaching, His life, His death, His resurrection, and His glorious ascension.
<Q: How did He do it by His incarnation?
>A: Through the incarnation, the Son of God has united the human and divine natures without confusion, without change, without division, and without separation. In this union in one Christ, which is surprising even for the angels, the divinity has healed the fallen humanity of Adam and so of all men. For since by man came death, by Man also came the resurrection of the dead. For as in Adam all die, even so in Christ all shall be made alive. (1 Corinthians 15:21-22)
<Q: How did He do it by His teaching?
>A: The teaching of Christ on salvation and blissful life is expressed in the Gospel of the Kingdom. This unchanged teaching is still proclaimed by the Holy Church. It helps us toward salvation if we accept it with all our heart.
<Q: How did He do it by His life?
>A: The life of the Lord leads toward salvation if we imitate Him spiritually: let us acquire the emotions, will, and Spirit of Jesus Christ, either directly or by imitating spiritually the lives of His saints. "Therefore I urge you, imitate me", says the Apostle Paul. (1 Corinthians 4:16)
<Q: How did He do it by His death?
>A: Through death, the Lord destroyed him who had the power of death, that is, the devil. (Hebrews 2:14) The death of the Lord leads us to salvation if we enter His Church through Baptism which symbolizes the death and resurrection of Christ. Three immersions in cold water symbolize His death and His stay in Hell for three days. The emergence from water symbolizes His glorious resurrection. Do you not know that as many of us as were baptized into Christ Jesus were baptized into His death? Therefore we were buried with Him through baptism into death, that just as Christ was raised from the dead by the glory of the Father, even so we also should walk in newness of life. (Romans 6:3-4)
>The death of the Lord leads us to salvation if we eat His true and pure Body and drink His true and pure Blood through the sacrament of the Holy Eucharist which is to be accomplished until His second and glorious coming. For I received from the Lord that which I also delivered to you: that the Lord Jesus on the same night in which He was betrayed took bread; and when He had given thanks, He broke it and said, “Take, eat; this is My body which is broken for you; do this in remembrance of Me.” In the same manner He also took the cup after supper, saying, “This cup is the new covenant in My blood. This do, as often as you drink it, in remembrance of Me.” For as often as you eat this bread and drink this cup, you proclaim the Lord’s death till He comes. (1 Corinthians 11:23-26)
<Q: How did He do it by His resurrection?
>A: Having destroyd the gates of Hell (1 Peter 3:19) and liberated the souls of the righteous, the Lord Jesus Christ destroyed death and opened for all repentant men the entrance to Heaven, where the thief entered first. (Luke 23:43) Through His resurrection, all men will be resurrected in the flesh on the Final and Great Day of Judgement. The impious will go into everlasting punishment, but the righteous into eternal life. (Matthew 25:46)
<Q: How did He do it by His ascension?
>A: Through the ascension, the Lord Jesus Christ resurrects as a man, rises up and elevates our human nature into Himself, above all heavens and sits at the right hand of the Father. Thus men can become partakers of the divine nature (2 Peter 1:4), which means gods by grace.
<Q: What is redemption or ransom?
>A: Ransom is the payment by which slaves and captives obtained freedom, and by which criminals were spared from punishment. In the Old Testament, ransom designated an amount of money paid by the Jews for the first-born. Consequently, those children who were consecrated to the divine ministery in the Temple were exempt from serving in the Temple. Therefore, ransom is a payment to liberate those who are not able to obtain freedom by their own means.
>Following the original sin, man became a prisoner of the devil and suffered the punishment for his sins. Christ, being without sin and dying for us on the cross, liberates us from the consequences of original sin, including death, and destroys the power of the devil over man.