Alma 5:38-50

38  Behold, I say unto you, that the good shepherd doth call you; yea, and in his own name he doth call you, which is the name of Christ; and if ye will not hearken unto the voice of the good shepherd, to the name by which ye are called, behold, ye are not the sheep of the good shepherd.
39  And now if ye are not the sheep of the good shepherd, of what fold are ye?  Behold, I say unto you, that the devil is your shepherd, and ye are of his fold; and now, who can deny this?  Behold, I say unto you, whosoever denieth this is a liar and a child of the devil.
40  For I say unto you that 
            whatsoever is good cometh from God, 
            and whatsoever is evil cometh from the devil.
41  Therefore, if a man bringeth forth good works he hearkeneth unto the voice of the good shepherd, and he doth follow him; but whosoever bringeth forth evil works, the same becometh a child of the devil, for he hearkeneth unto his voice, and doth follow him.
42  And whosoever doeth this must receive his wages of him; therefore, for his wages he receiveth death, as to things pertaining unto righteousness, being dead unto all good works.

Alma 5:38-42 (Emphasis mine)

(Formatting in verse 40 from The Book of Mormon - A Reader's Edition by Grant Hardy, pg. 263)

Alma(2) tells the people that they are being called by Christ.  If they listen to his call, they will become his sheep.  Once again, the image of Christ as the shepherd is a common thread in the scriptures.

1  THE LORD is my shepherd; I shall not want.

Psalms 23:1 (Emphasis mine)

6  O come, let us worship and bow down: let us kneel before the LORD our maker.
7  For he is our God; and we are the people of his pasture, and the sheep of his hand...

Psalms 95:6-7 (Emphasis mine)

10  Behold, the Lord GOD will come with strong hand, and his arm shall rule for him: behold, his reward is with him, and his work before him.
11  He shall feed his flock like a shepherd: he shall gather the lambs with his arm, and carry them in his bosom, and shall gently lead those that are with young.

Isaiah 40:10-11 (Emphasis mine)

36  ¶ But when he saw the multitudes, he was moved with compassion on them, because they fainted, and were scattered abroad, as sheep having no shepherd.

Matthew 9:36 (Emphasis mine)

14  I am the good shepherd, and know my sheep, and am known of mine.

John 10:14 (Emphasis mine)

Alma(2) gives a very simple guide to determine good from evil.  If it comes from God; if it is not good, it comes from the devil.  

But what of those who don't answer His call?  What is their fate?

Alma(2) doesn't mince words.  The devil is the shepherd of those who ignore the call of the Good Shepherd.  They are a part of his fold and listen to his voice.  In short, the wages of sin are death; this is the spiritual death when they wicked are cut off from the presence of God throughout all eternity.

The ultimate question being asked is who is our shepherd?  Who do we follow?  There's only two choices.  One, Christ, leads to eternal life.  The other, the devil, leads us to spiritual death.  

Hugh Nibley emphasized this point.  "There's no alternative ever mentioned between these two. When Alma speaks, or anybody else in the Book of Mormon, it's the one or the other." (Emphasis mine) 

41  Ye do the deeds of your father.  Then said they to him, We be not born of fornication; we have one Father, even God.
42  Jesus said unto them, If God were your Father, ye would love me: for I proceeded forth and came from God; neither came I of myself, but he sent me.
43  Why do ye not understand my speech?  even because ye cannot hear my word.
44  Ye are of your father the devil, and the lusts of your father ye will do.  He was a murderer from the beginning, and abode not in the truth, because there is no truth in him.  When he speaketh a lie, he speaketh of his own: for he is a liar, and the father of it.

John 8:41-44 (Emphasis mine)

23  For the wages of sin is death; but the gift of God is eternal life through Jesus Christ our Lord.

Romans 6:23 (Emphasis mine)

Now Alma(2) gives us his testimony.

43  And now, my brethren, I would that ye should hear me, for I speak in the energy of my soul; for behold, I have spoken unto you plainly that ye cannot err, or have spoken according to the commandments of God.
44  For I am called to speak after this manner, according to the holy order of God, which is in Christ Jesus; yea, I am commanded to stand and testify unto this people the things which have been spoken by our fathers concerning the things which are to come.

Alma 5:43-44 (Emphasis mine)

He once again is emphasizing that he is doing this through commandment.  He is speaking as passionately as he can.  And he has used plain language so they would understand.

45  And this is not all.  Do ye not suppose that I know of these things myself?  Behold, I testify unto you that I do know that these things whereof I have spoken are true.  And how do ye suppose that I know of their surety?
46  Behold, I say unto you they are made known unto me by the Holy Spirit of God.  Behold, I have fasted and prayed many days that I might know these things of myself.  And now I do know of myself that they are true; for the Lord God hath made them manifest unto me by his Holy Spirit; and this is the spirit of revelation which is in me.

Alma 5:45-46 (Emphasis mine) 

As a part of his testimony he asks "Do you think I just made these things up?"  Then he answers the question.  "No.  I give you my testimony these things are true.  They have been made known to me through  the Holy Spirit.  I fasted and prayed many days, and these words were made known to me through the Holy Spirit."

This is key.  He wants the people to understand the source of his words.  They are the words of the Lord, given to the leader of His church, Alma(2) to be given to the people.  

I can almost hear the passion and power of his words as he preaches and testifies to the people.  I can hear Alma(2) clearly testifying, doing all he can to convey the spirit behind his words, which would serve as an additional testimony to their truthfulness.

9  But as it is written, Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him.
10  But God hath revealed them unto us by his Spirit: for the Spirit searcheth all things, yea, the deep things of God.
11  For what man knoweth the things of a man, save the spirit of man which is in him?  even so the things of God knoweth no man, but the Spirit of God.
12  Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.
13  Which things also we speak, not in the words which man's wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual.
14  But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.
15  But he that is spiritual judgeth all things, yet he himself is judged of no man.
16  For who hath known the mind of the Lord, that he may instruct him?  But we have the mind of Christ.

1 Corinthians 2:9-16 (Emphasis mine)

47  And moreover, I say unto you that it has thus been revealed unto me, that the words which have been spoken by our fathers are true, even so according to the spirit of prophecy which is in me, which is also by the manifestation of the Spirit of God.
48  I say unto you, that I know of myself that whatsoever I shall say unto you, concerning that which is to come, is true; and I say unto you, that I know that Jesus Christ shall come, yea, the Son, the Only Begotten of the Father, full of grace, and mercy, and truth.  And behold, it is he that cometh to take away the sins of the world, yea, the sins of every man who steadfastly believeth on his name.
49  And now I say unto you that this is the order after which I am called, yea, to preach unto my beloved brethren, yea, and every one that dwelleth in the land; yea, to preach unto all, both old and young, both bond and free; yea, I say unto you the aged, and also the middle aged, and the rising generation; yea, to cry unto them that they must repent and be born again.
50  Yea, thus saith the Spirit: Repent, all ye ends of the earth, for the kingdom of heaven is soon at hand; yea, the Son of God cometh in his glory, in his might, majesty, power, and dominion.  Yea, my beloved brethren, I say unto you, that the Spirit saith: Behold the glory of the King of all the earth; and also the King of heaven shall very soon shine forth among all the children of men.

Alma 5:47-50 (Emphasis mine)

Alma(2) not only testifies of the truthfulness of his words, but he also testifies that the words which have been spoken through the years were also true and inspired of God.

He knows that his words and prophecies, especially concerning Christ, are true.  He testifies of the coming of Christ.  This is because of the calling and position he holds as head of the church.

He teaches because he was called to do this.  His message and words were inspired by the Holy Spirit.

5  Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations.

Jeremiah 1:5 (Emphasis mine)

14  ¶ Then answered Amos, and said to Amaziah, I was no prophet, neither was I a prophet's son; but I was an herdman, and a gatherer of sycomore fruit:
15  And the LORD took me as I followed the flock, and the LORD said unto me, Go, prophesy unto my people Israel.

Amos 7:14-15 (Emphasis mine)

21  And going on from thence, he saw other two brethren, James the son of Zebedee, and John his brother, in a ship with Zebedee their father, mending their nets; and he called them.

Matthew 4:21 (Emphasis mine)

16  Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you

John 15:16 (Emphasis mine)

23  And they appointed two, Joseph called Barsabas, who was surnamed Justus, and Matthias.
24  And they prayed, and said, Thou, Lord, which knowest the hearts of all men, shew whether of these two thou hast chosen,

Acts 1:23-24 (Emphasis mine)

7  Whereunto I am ordained a preacher, and an apostle, (I speak the truth in Christ, and lie not;) a teacher of the Gentiles in faith and verity.

1 Timothy 2:7 (Emphasis mine)

4  And no man taketh this honour unto himself, but he that is called of God, as was Aaron.

Hebrews 5:4 (Emphasis mine)

And so ends the testimony of Alma(2).