The are two orders of priesthood in the Old Testament.
The are two kinds of priesthood in the New Testament.
Some people assume that the apostolic Church had no priests because the topic is not discussed in the New Testament.
(These same people are all too happy to add things to their Christian practice in areas that the New Testament is silent about, but they reject the priesthood. This is wrongheaded.)
But when the New Testament is silent about a topic we should turn to the Early Church Fathers for guidance— they have much to say about the priesthood from the very earliest of times.
The question is how to explain the appearance of priests in the early history of the Church. In looking at the characteristics and attributes of priests, we see that all the elements were indeed present from day one of the Church.
The Greek word "presbuteros", often translated "elder" or "presbyter", is used in the New Testament for Jewish religious leaders and for ordained Christian ministers — those who rule over the people. It is also used when referring to a person older than another. This matches the role of bishop rather well but says nothing about the priesthood.
The New Testament has no description of priests and their functions. But the earliest Church Fathers do describe this and this was passed-down to them from the apostles. This highlights a flaw in looking only to scripture and in rejecting Tradition.The Bible is incomplete — it was never intended to describe every aspect of Christian life. Thus, we must study the Churchto have a complete view of Christianity and faith.
Priests lead the congregation in worship.
The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break, is it not the communion of the body of Christ? (1 Corinthians 10:16)
The celebration of the Eucharist was not just happening on its own — ministers presided over it. And from the writings of the Eartly Church Fathers we learn that these were ordained ministers.
Priests offer sacrifice for sin. That is one of the aspects of the Eucharist — the one-time sacrifice of Jesus for our salvation is made present.
Priests are set aside, ordained, and anointed for their task. It is a lifetime calling.
Priests receive tithes from the people.
And verily they that are of the sons of Levi, who receive the office of the priesthood, have a commandment to take tithes of the people according to the law, that is, of their brethren, though they come out of the loins of Abraham. (Hebrews 7:5)
Priests are consecrated to God, they offer sacrifice, and they administer the sacraments. That's all there is to it.
Any Church which believes in the Eucharist as literally Christ's body and blood, these Churches have priests. They may not be called by that name.
The apostle Peter speaks of Christians as priests using the same word used for Old Testament priests.
Ye also, as lively stones, are built up a spiritual house, an holy priesthood, to offer up spiritual sacrifices, acceptable to God by Jesus Christ. (1 Peter 2:5)
But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should show forth the praises of him who hath called you out of darkness into his marvellous light. (1 Peter 2:9)
The book of Revelation refers to Christians as priests.
Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years. (Revelation 20:6)
And hast made us unto our God kings and priests: and we shall reign on the earth. (Revelation 5:10)
Christians at large perform their priestly role by various acts of faith, service, and devotion.
I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service. (Romans 12:1)
Yea, and if I be offered upon the sacrifice and service of your faith, I joy, and rejoice with you all. (Philippians 2:17)
But I have all, and abound: I am full, having received of Epaphroditus the things which were sent from you, an odour of a sweet smell, a sacrifice acceptable, wellpleasing to God. (Philippians 4:18)
By him therefore let us offer the sacrifice of praise to God continually, that is, the fruit of our lips giving thanks to his name. (Hebrews 13:15)