Abinadi explained that this passage refers to the seed of Christ, particularly his prophets, and preeminently, the Savior himself:
'…all the holy prophets ever since the world began? I say unto you that they are his seed.
And these are they who have published peace, who have brought good tidings of good, who have published salvation; and said unto Zion: Thy God reigneth!
And O how beautiful upon the mountains were their feet!
And again, how beautiful upon the mountains are the feet of those that are still publishing peace!
And again, how beautiful upon the mountains are the feet of those who shall hereafter publish peace, yea, from this time henceforth and forever!
And behold, I say unto you, this is not all. For O how beautiful upon the mountains are the feet of him that bringeth good tidings, that is the founder of peace, yea, even the Lord, who has redeemed his people; yea, him who has granted salvation unto his people;
For were it not for the redemption which he hath made for his people, which was prepared from the foundation of the world, I say unto you, were it not for this, all mankind must have perished.' (Mosiah 15:13-19)
This scripture applies to the prophets and apostles of our day. How beautiful upon the Rocky Mountains are the feet of those great men whose lives have been dedicated to bringing good tidings and publishing peace! They continue to proclaim the same message that Abinadi did, that salvation comes through the sacrifice of the Only-Begotten, to break the bands of death and satisfy the demands of justice. When we raise our arm to the square to sustain the leaders of the Church, the words of Abinadi and Isaiah should come to mind, how beautiful upon the mountains are the feet of those who shall hereafter publish peace!
Mark E. Petersen
"Have you ever asked yourselves who these people are, who preach the gospel of peace and whose feet are so beautiful upon the mountains? Abinadi, in the Book of Mormon, gives us the explanation. These people are the prophets of God - they who preach the gospel of the Prince of Peace, the Lord Jesus Christ." [Quoting Mosiah 15:13-18]
"So spoke Abinadi. The prophets, then are the servants of Jesus Christ and have been from the beginning of time. . . .We honor them. We shall follow them, and through them we shall work out our salvation here on earth in the Lord's own way." (LDS Church News, Deseret News, Mar 30, 1996)
Jeffrey R. Holland
"These familiar passages, written first by Isaiah but spoken of and inspired by Jehovah himself, are often applied to anyone—especially missionaries—who bring the good tidings of the gospel and publish peace to the souls of men. There is nothing inappropriate about such an application, but it is important to realize—as the prophet Abinadi did—that in its purest form and original sense, this psalm of appreciation applies specifically to Christ. It is he and only he who ultimately brings the good tidings of salvation. Only through him is true, lasting peace published. To Zion, in both the old and new Jerusalems, it is Christ who declares, 'Thy God reigneth!' It is his feet upon the mountain of redemption that are beautiful." (Christ And The New Covenant, p. 286 – 287)