The Protestant struggles with this because of Sola Scriptura (and a natural tendency in many Protestant circles to deny a belief if not
explicit in Scripture, only if taught by Catholics). Jesus gave the commission to consecrate the Eucharist to his apostles when He said to them in the upper room, “Do this in memory of me.” The role of priest in this manner performing “sacrifice” in the person of Christ, goes all the way back to the Old Testament, in which only priests were allowed to perform sacrifices. (article at
Jimmy Akin’s website, or even better—this
article by Jimmy–just search for “sacrifice” to read pertinent paragraphs)
The Catechism says this on baptism being able to be applied by a lay person in unordinary circumstances:
1256 The ordinary ministers of Baptism are the bishop and priest and, in the Latin Church, also the deacon.57 In case of necessity, anyone, even a non-baptized person, with the required intention, can baptize58 , by using the Trinitarian baptismal formula. The intention required is to will to do what the Church does when she baptizes. The Church finds the **reason for this possibility in the universal saving will of God and the necessity of Baptism for salvation.**59
Click here to read the footnote cross-references.
Fracturing Scripture from the light of Tradition from which it was written, which can be seen in the life of the Church, results in a certain blindness to what various Scripture verses mean.