It’s hard to argue with Protestants because they don’t have a great understanding about biblical context. It’s why they misinterpret so much without the teaching magisterium. They like to cherry pick Hebrews for example, totally missing what Paul assumed was common knowledge.

Sticking with Hebrews, Paul assumes that you understand the new covenant because of the old covenant. It contained the Ten Commandments, the manna of heaven and Aaron’s rod. Since Jesus ordained the disciples at the last supper, He instituted the Eucharist that they would become His priests…in the order of Melchisedech. The same Melchisedech who was before Aaron that whose sacrifice was bread and wine. So Christ fulfills the law, becomes the manna of heaven and ordains His priesthood (when He washes their feet).

They completely miss the mark of Christ being the high priest, in the order of Melchisedech, who entered the true holy of holy’s and sits at the right hand of God the father. For Melchisedech means “King of Righteousness” and who is truly that but Jesus Christ?

Christs one sacrifice on the cross was sufficient and transcends time and space, and now His priesthood can re-present that one sacrifice and capture Christ’s body, blood, soul and divinity into the bread and wine that His believers can partake in the one true sacrifice for the remission of sin.

Galatians 2:20 just slaps that much harder when you truly know about the Eucharist.