Catholicism[edit]
Catholics find the roots of their priesthood in the tradition of Melchizedek. (CCC 1544)
[7] In
Genesis 14:18, Melchizedek offers a sacrifice of bread and wine. Christ therefore fulfilled the prophecy of Ps 110:4, that he would be a priest "after the order of Melchizedek," at the
Last Supper, when he broke and shared bread with his
disciples. Catholics take seriously Christ's command that the Apostles should "do this in memory of Me". As such, the Catholic Church continues to offer the same sacrifice of bread and wine at
Mass, as part of the
Sacrament of the
Eucharist.
This is the sole origin of a Catholic priesthood.
It is certainly not paganism, not even the Aaronic priesthood of the OT,but something considered of a higher calling, and something that precedes the Law of Moses and the rituals involved therein. Such is explained in Hebrews.
Priests in all cultures are commissioned with rituals, and most definitely, the Last Supper must be understood as ritualized behavior that was to continue in the Church created by the sacrifice of Jesus.
To be sure there have from the very beginning been very heterodox understandings of virtually any Christian doctrine from the beginning, and Christian rituals are not the exception. If Protestants want to find ancient ideals that differed from what became considered orthodox, definitely history of Christianity contains a plethora of heterodox ideals. Islam itself is an example of how heterodox ideals can lead to very different understandings of who Christ is.
The fact that Islam exists also shows the danger of straying too far from the traditional orthodoxies, too far in writing off the mainstream views as hopelessly corrupted apostasy.