Thank you for answering! I do have one more question: How was Jesus able to give his disciples his body and blood for forgiveness of sins at the Last Supper when he had not yet shed his blood on the cross? From my understanding Christ's death is what justified us before God and allowed our sins to be forgiven.
Sure, no problem. There's a few ways we can talk about this, but perhaps the easiest way of thinking of it this: In the institution, we do have all the elements - There are bread and wine, Christ is truly present, and His promise of forgiveness of sins is real and true. This is what makes a Sacrament.
In the institution, Christ is locally present according to His state of humiliation. However, after His death and resurrection, He is sacramentally present according to His state of exaltation. That is, in his earthly ministry He is locally present - He walked and talked among us. But in His glorified body, He fills all things, according to His divinity. He doesn't seize to be human, but is fully man and fully God forever. And in accordance with His exalted state, He can and is sacramentally present in every Eucharist in every location of all time.
It's certainly Christ crucified who brought about our salvation - and really, His whole earthly life. He fulfilled the Law in our place, walking in perfect obedience to the Father, even to the point of the cross, where He took our sins upon Himself and was nailed to the cross, and our sins were crucified with Him. But all of those preceding this event, such as the faithful people in the OT, looked forward to this promise in faith, and they were justified by it. And, likewise, all of us now who look back at this event and believe in it are also justified. So all are justified by faith, by God's grace.
Blessings +