When Melchizedek Preached Repentance, His People Responded and Established Peace in the City of Salem

Alma 13:17–18  

17 Now this Melchizedek was a king over the land of Salem; and his people had waxed strong in iniquity and abomination; yea, they had all gone astray; they were full of all manner of wickedness;
18 But Melchizedek having exercised mighty faith, and received the office of the high priesthood according to the holy order of God, did preach repentance unto his people.  And behold, they did repent; and Melchizedek did establish peace in the land in his days; therefore he was called the prince of peace, for he was the king of Salem; and he did reign under his father.

Elder Bruce R. McConkie wrote:

“To the man Melchizedek goes the honor of having his name used to identify the Holy Priesthood after the Order of the Son of God, thus enabling men ‘to avoid the too frequent repetition’ of the name of Deity (D&C 107:2–4). Of all God’s ancient high priests ‘none were greater’ (Alma 13:19). His position in the priestly hierarchy of God’s earthly kingdom was like unto that of Abraham (Hebrews 7:4–10), his contemporary whom he blessed (Genesis 14:18–20; Hebrews 7:1; JST, Genesis 14:17–40), and upon whom he conferred the priesthood (D&C 84:14). Indeed, so exalted and high was the position of Melchizedek in the eyes of the Lord and of his people that he stood as a prototype of the Son of God Himself, the Son who was to arise ‘after the similitude of Melchisedec’ (Hebrews 7:15). Both bore the titles, Prince of Peace and King of Heaven—meaning King of Peace (Alma 13:18; JST, Genesis 14:33, 36)—and both were joint-heirs of the Father’s kingdom.”

(Mormon Doctrine, 2nd ed. [1966], 474–75.)