Mosiah 15:9-18

9  Having ascended into heaven, having the bowels of mercy; being filled with compassion towards the children of men; standing betwixt them and justice; having broken the bands of death, taken upon himself their iniquity and their transgressions, having redeemed them, and satisfied the demands of justice.
10  And now I say unto you, who shall declare his generation?  Behold, I say unto you, that when his soul has been made an offering for sin he shall see his seed.  And now what say ye?  And who shall be his seed?
11  Behold I say unto you, that whosoever has heard the words of the prophets, yea, all the holy prophets who have prophesied concerning the coming of the Lord—I say unto you, that all those who have hearkened unto their words, and believed that the Lord would redeem his people, and have looked forward to that day for a remission of their sins, I say unto you, that these are his seed, or they are the heirs of the kingdom of God.
12  For these are they whose sins he has borne; these are they for whom he has died, to redeem them from their transgressions.  And now, are they not his seed?
13  Yea, and are not the prophets, every one that has opened his mouth to prophesy, that has not fallen into transgression, I mean all the holy prophets ever since the world began?  I say unto you that they are his seed.
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;

Mosiah 15:9-18 (Emphasis mine)

(Note - poetic format beginning with v.14 from Book of Mormon - a Reader's Edition by Grant Hardy, pgs. 213-214)

Abinadi tells us that after Christ's death, he ascended to Heaven and stood between them (the children of men) and justice.  In the words of Hugh Nibley:

"Who will sponsor this particular generation? These characters, do you trust them? Who will vouch for them? Then it says he introduces them as his zera, which means 'progeny, one's very own.' All the way through the Old Testament seed is freely translated that way because it means seed in many senses. This is what has happened. Now, who shall vouch for this generation? ... He shall see his progeny and accept them as his very own." (Emphasis mine)  Lecture 35: Mosiah 15-16, Hugh W. Nibley, Maxwell Institute, accessed July 4, 2011.

By accepting and following the teachings of Christ, we become His children.  For us, He is no longer the Son.  He becomes our eternal Father.  He will stand up for us and defend us when justice comes calling and makes it demands.  He  will intercede for us.

Beginning in verse 15, Abinadi reminds us that all the prophets have testified of Christ.  Not only that, but that in the future, all prophets will testify of Christ (v 17).  Finally, Christ will be the ultimate prophet testifying of Himself (v 18).  (For more information, see Abinadi: The Message and the Martyr, Todd B. Parker, Maxwell Institute, accessed July 4, 2011.) 

The scriptures support the words of Abinadi.

8  He will swallow up death in victory; and the Lord GOD will wipe away tears from off all faces; and the rebuke of his people shall he take away from off all the earth: for the LORD hath spoken it.

Isaiah 25:8 (Emphasis mine)

4  ¶ Surely he hath borne our griefs, and carried our sorrows: yet we did esteem him stricken, smitten of God, and afflicted.
5  But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed.

Isaiah 53:4-5 (Emphasis mine)

10  ¶ Yet it pleased the LORD to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the LORD shall prosper in his hand.
11  He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities.

Isaiah 53:10-11 (Emphasis mine)

20  But while he thought on these things, behold, the angel of the Lord appeared unto him in a dream, saying, Joseph, thou son of David, fear not to take unto thee Mary thy wife: for that which is conceived in her is of the Holy Ghost.
21  And she shall bring forth a son, and thou shalt call his name JESUS: for he shall save his people from their sins.

Matthew 1:20-21 (Emphasis mine) 

32  Behold, the hour cometh, yea, is now come, that ye shall be scattered, every man to his own, and shall leave me alone: and yet I am not alone, because the Father is with me.
33  These things I have spoken unto you, that in me ye might have peace.  In the world ye shall have tribulation: but be of good cheer; I have overcome the world.

John 16:32-33 (Emphasis mine) 

20  But now is Christ risen from the dead, and become the firstfruits of them that slept.

21  For since by man came death, by man came also the resurrection of the dead.

22  For as in Adam all die, even so in Christ shall all be made alive.

1 Corinthians 15:20-22 (Emphasis mine)

8  Though he were a Son, yet learned he obedience by the things which he suffered;
9  And being made perfect, he became the author of eternal salvation unto all them that obey him;

Hebrews 5:8-9 (Emphasis mine)

13  For if the blood of bulls and of goats, and the ashes of an heifer sprinkling the unclean, sanctifieth to the purifying of the flesh:
14  How much more shall the blood of Christ, who through the eternal Spirit offered himself without spot to God, purge your conscience from dead works to serve the living God?
15  And for this cause he is the mediator of the new testament, that by means of death, for the redemption of the transgressions that were under the first testament, they which are called might receive the promise of eternal inheritance.

Hebrews 9:13-15 (Emphasis mine)

Why does Abinadi continue, responding the way he does. I turn to the words of Todd Parker.

"That's his seed—those who believe the prophets, those who know that Jehovah will come down—and that is Christ—and he will be our Savior ... The prophets are Christ's seed. And notice in verse 14, Abinadi answers the question raised at the beginning: 'And these are they who have published peace.' Remember, they asked, 'What does Isaiah mean here?' And he gave this big long speech.  He was supposed to be on the defensive, but he was really on the offensive, saying, 'Wait a minute, don't interrupt me. I haven't finished. I have to give this speech.' " (Emphasis mine)

Abinadi: The Message and the Martyr, Todd B. Parker, Maxwell Institute, accessed July 4, 2011.