Jesus died, past tense.
Jesus rose. He conquered death.
He is in heaven a risen Savior, seated at God's right hand. It's not the sacrificing that saves, but the death. The sacrificing continuing means that it's not done, the victim has not died. If the sacrifice is not yet dead, there can be no forgiveness of sins and victory over death.
We are not participating in His death. We who are saves are participating in being seated with Him in the heavenly places.
Ephesians 1:15-23 15 For this reason, because I have heard of your faith in the Lord Jesus and your love toward all the saints, 16 I do not cease to give thanks for you, remembering you in my prayers, 17 that the God of our Lord Jesus Christ, the Father of glory, may give you the Spirit of wisdom and of revelation in the knowledge of him, 18 having the eyes of your hearts enlightened, that you may know what is the hope to which he has called you, what are the riches of his glorious inheritance in the saints, 19 and what is the immeasurable greatness of his power toward us who believe, according to the working of his great might 20 that he worked in Christ when he raised him from the dead and seated him at his right hand in the heavenly places, 21 far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in the one to come. 22 And he put all things under his feet and gave him as head over all things to the church, 23 which is his body, the fullness of him who fills all in all.
Ephesians 2:4-7 4 But God, being rich in mercy, because of the great love with which he loved us, 5 even when we were dead in our trespasses, made us alive together with Christ by grace you have been saved 6 and raised us up with him and seated us with him in the heavenly places in Christ Jesus, 7 so that in the coming ages he might show the immeasurable riches of his grace in kindness toward us in Christ Jesus.
I do not dispute obviously that Jesus rose from the dead. What you allude to is a mystery.
But, I quoted passages that support my understanding. The participation is not "in being seated at the right hand of the Father."
1 Cor. 10:16 - "The cup of blessing that we bless, is it not a participation in the blood of Christ? The Bread that we break, is it not a participation in the body of Christ?"
Clearly Paul is writing after the death and resurrection of Jesus, yet he says the bread and wine are a participation in Christ's body and blood. In order to understand the Bible you have to reconcile all of its parts. You cannot simply reject or ignore parts of the Bible if they do not fit your understanding.
That being said, I beieve we are all struggling in good faith to grow in faith. Peace to you.