It's funny I wondered about that before and I've understood it the same way as you and I believe you are correct. I'm not a priest just a person in search of the truth..:)
In dying Jesus destroyed death, In rising Jesus restored our life. So when Jesus died he destroyed death itself. Sin leads to death, Forgiveness of our Sin restores our life. So Jesus had victory over both. And the power of God is MUCH MUCH greater than the power of the evil one, never forget that. Look for the good and there you will see God.
We will always have to tackle sin because that's inherant in who we are as humans. We are made of body (flesh) and spirit and Jesus even points that out that our flesh makes us weak and often sleeping. He said to Peter that the spirit is willing but the flesh is weak But when our spirit is awakened, we can deny those fleshy moments which and bind us by sin. Jesus shows us to fast and prayer to help us with sin. We can do that by receiving the sacraments and doing our best to stay close to God and Trusting in Him, drawing strength from him, following in Jesus ways rather than the ways of the world. Yes we can chose not to sin, but it is a given it is impossible without God working in our lives. We can have God working quite directly by being baptised as a child of God (receiving new spiritual life In Christ as we are 'born again') and allowing the Holy spirit to make a dwelling in us through knowing Jesus, growing in our faith and dying in friendship with God. That takes obedience and discipline on our part and Gods mercy.
SIn will always be a temptor because we have human frailty, it says that in the Lords prayer , but we pray to God for deliverance from it.
I agree with you on that about purgatory.. The people before Jesus walked on earth did their best to resist sins and would give up their prized animals to priest as sin offerings, but before Jesus death, their rewards were made in the form of blessings and some were held in prison. Remember Jesus speaking to Moses and Elijah at the transfiguration. After Jesus death rewards are made in eternal life in heaven and the souls held in the earth were preached to (the 3 days that Jesus was in the grave) and also rose with Jesus. Of course that is all part of the mystery of the death, burial and resurrection of Jesus.
1 Peter 3:18 For Christ also suffered once for sins, the righteous for the unrighteous, that he might bring us to God, being put to death in the flesh but made alive in the spirit, 19 in which[c] he went and proclaimed to 'the spirits in prison', 20 because they formerly did not obey, when God's patience waited in the days of Noah, while the ark was being prepared, in which a few, that is, eight persons, were brought safely through water. 21 Baptism, which corresponds to this, now saves you, not as a removal of dirt from the body but as an appeal to God for a good conscience, through the resurrection of Jesus Christ, 22 who has gone into heaven and is at the right hand of God, with angels, authorities, and powers having been subjected to him.
Jesus did not come to abolish the law but to fulfill.
We are saved by our baptism but we still need a cleansing of our sins in order to be purified because sins cannot belong in heaven. That's why there is purgatory for the purification of sins.
It took me awhile to figure this out but, as Christ was an one time offering for the removal of sins, we now offer ourselves, our Christ-led lives, our prayers up to Him and seek him for the removal of our sins. The process begins when we are baptized and welcomed into the church.
Well anyway that's what I wanted to share on it.