What is the biblical basis for in the catholic theology of a priest being in "persona christi"? What is the biblical basis for in the catholic theology of a priest being in "persona christi"?

The idea that only a Priest can conduct the NT Passover meal that Christ told us to "do in remembrance of Him" was for all believers surely?

Why is it that in Catholicism the Priest is essentially "in persona Christi" and is therefore the only way for a "valid" communion meal?

Where in the Bible is the justification for a Priest being in persona Christi? (an emphasis especially on the Eucharistic sacrament please, but also interested in the theology as a whole).

Thank you.
A priest is not being in "persona Christi" but the priest ACTS in the person of Christ(persona Christi) in pronouncing the words that comprise part of a sacramental rite.

For example, in the Mass, the Words of Institution, by which the bread becomes the Body of Christ and the wine becomes the Precious Blood. The priest and bishop ACT in the person of Christ the head in their leadership of the Church.

2 Corinthians 2:10


  Whomever you forgive anything, so do I. For indeed what I have
  forgiven, if I have forgiven anything, has been for you in the
  presence of Christ,


Naturally, therefore, without consulting the Greek text, this verse would not necessarily leap out at one as being about the priesthood. But the Greek text says that St Paul forgave sins “en prosopo Christou”.

“Prosopon” in Greek literally means “face”. In the Trinitarian debates of the 4th Century, the Greeks used it to translate Tertullian’s use of the latin term “persona” for what we now commonly refer to as “the Persons” of the Holy Trinity. Working the other way, when Jerome translated made his new Latin translation of the bible, he used “persona” to translate “prosopon” in 2 Corinthians 2:10, thus making the text read:


  10 cui autem aliquid donatis et ego nam et ego quod donavi si quid
  donavi propter vos in persona Christi 11 ut non circumveniamur a
  Satana non enim ignoramus cogitationes eius


In English translations, both the Douay-Rheims and the King James Bible follow suit in translating “en prosopo Christou” as “in the person of Christ.”

As you can see, this certainly lends strong support to the Catholic doctrine of the priesthood (cf. CCC p1548 quoting 24 Pius XII, Mediator Dei: “Now the minister, by reason of the sacerdotal consecration which he has received, is truly made like to the high priest and possesses the authority to act in the power and place of the person of Christ himself (virtute ac persona ipsius Christi).)

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