A Sacrament is a visible sign instituted by Christ to give us grace. The Priesthood has always been a Sacrament in the Church. It wasn’t until Martin Luther, the Father of Protestantism, who in the 16th century decide to teach his own doctrines and remove 7 books from the Bible along with discarding the Priesthood, the Real Presence in the Eucharist, on top of claiming that the pope was the antichrist. Those who put their faith in the teachings of Luther are not following the teachings of the Church in these matters. Thus Lutheranism is founded on the teachings of Luther, who was an ex-Catholic priest.
But in the Old Testament there were three levels of the Priesthood: The High Priest, The Ministerial Priesthood, and the Common Priesthood of the people. Likewise, in the New Testament, Christ is now the High Priest, the Clergy are the Ministerial Priesthood (who feed and tend the sheep), and we the laity and religious are the Common Priesthood, where we offer up our works, joys and sufferings in union with the sacrifice of Christ. The Ministerial Priesthood (deacons, priests, bishops, and popes) are charged with administering the sacraments. A valid priesthood is necessary to confect a valid Eucharist. After all, not anyone can turn ordinary bread and wine into the Body, Blood, Soul and Divinity of Christ in the Eucharist. For this we need a validly ordained priest. Christ instituted this Sacrament at the Last Supper.