The only priests in the New Testament are those that served in the temple in Jerusalem. There were no priests among the brethren. So how did the early church moved from a simple pure faith to one with priests?
The Bible gave us episkope depending on the English translations one is reading that is either presbyters or bishops. Then there is diakonos which is translated either as deacons or elders. [1 Tim. 3] These were not spiritual leaders but rather guardians of truth, organizers, and servants.
Oddly enough it was the heathen Lucian (born about 120 died about 180 AD) in his satires that gave the Christians priests. In “De morte Peregrini,” describes the unwearied care of the Christians for their “imprisoned brethren” the “heaps of presents” brought to them; and the “testimonies of sympathy” even by messengers from great distances; but all, of course, in Lucian’s view, out of mere good-natured enthusiasm.
So our priests come from a misunderstanding by the unbelievers around them.
42 And Jesus called them to him and said to them, “You know that those who are supposed to rule over the Gentiles lord it over them, and their great men exercise authority over them. 43 But it shall not be so among you; but whoever would be great among you must be your servant, 44 and whoever would be first among you must be slave of all. 45 For the Son of man also came not to be served but to serve, and to give his life as a ransom for many.” Mark 10:42-45
We were each to be our OWN priest. But there are always those who would lord of others claiming special calling or gifts.
But you are a chosen race, a royal priesthood, a holy nation, God’s own people, that you may declare the wonderful deeds of him who called you out of darkness into his marvelous light. 1Pet. 2:9