I love how Abinadi takes a question intended to trip him up by the priests of Noah and turns it into a powerful testimony of Christ. After quoting Isaiah’s powerful prophecy of the atonement and crucifixion of the savior, Abinadi links his teaching back to the original question. He emphasizes that all those who believe and preach of Jesus are his sons and daughters and are the fulfilment of prophecy. So Abinadi illustrates powerfully how all things point back to Christ.
I also have always been struck by the triple repetition in these verses. Abinadi says how beautiful were their feet, are the feet, and are the feet of those who shall. Such triplets occur in a few places in the Book of Mormon and really emphasis the unchanging and eternal nature of God.
14 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!
15 And O how beautiful upon the mountains were their feet!
16 And again, how beautiful upon the mountains are the feet of those that are still publishing peace!
17 And again, how beautiful upon the mountains are the feet of those who shall hereafter publish peace, yea, from this time henceforth and forever!
18 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;
19 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.