Alma 42:28-31

28  If he has desired to do evil, and has not repented in his days, behold, evil shall be done unto him, according to the restoration of God.
29  And now, my son, I desire that ye should let these things trouble you no more, and only let your sins trouble you, with that trouble which shall bring you down unto repentance.
30  O my son, I desire that ye should deny the justice of God no more.  Do not endeavor to excuse yourself in the least point because of your sins, by denying the justice of God; but do you let the justice of God, and his mercy, and his long-suffering have full sway in your heart; and let it bring you down to the dust in humility.
31  And now, O my son, ye are called of God to preach the word unto this people.  And now, my son, go thy way, declare the word with truth and soberness, that thou mayest bring souls unto repentance, that the great plan of mercy may have claim upon them.  And may God grant unto you even according to my words.  Amen.

Alma 42:28 - 31 (Emphasis mine)

Alma(2) emphasizes that if a person desires and chooses to do evil, that is what he will get in return.

Choice has been a major theme throughout Alma(2)'s epistle.  He emphasizes that God does not force man to be evil (nor righteous  for that matter).  We all have choices to make.  What we reap  is based on the choices we freely make throughout our lifetime.  The beauty of this is that a way has been provided to us to obtain mercy and return to the presence of God. 

Alma(2) concludes his epistle calling upon Corianton to repent, to cease to "deny the justice of God."  The time had come for Corianton to humble himself before God and to "let the justice of God, and his mercy .. have full sway in your heart..."  (v30).  Now was the time for him to repent of his sin.  

Alma(2) calls upon Corianton to continue his work, calling the people  to repentance so that the "plan of mercy may have claim upon them."  (v31)

Paul wrote:

8  For though I made you sorry with a letter, I do not repent, though I did repent: for I perceive that the same epistle hath made you sorry, though it were but for a season.
9  Now I rejoice, not that ye were made sorry, but that ye sorrowed to repentance: for ye were made sorry after a godly manner, that ye might receive damage by us in nothing.
10  For godly sorrow worketh repentance to salvation not to be repented of: but the sorrow of the world worketh death. 

2 Corinthians 7:8-10 (Emphasis mine)

Paul reinforces Alma(2)'s words about repentance.  We must humble ourselves before God.  But being sorry isn't enough.  We must have a "godly" sorrow.  

James wrote:

8  Draw nigh to God, and he will draw nigh to you.  Cleanse your hands, ye sinners; and purify your hearts, ye double minded.
9  Be afflicted, and mourn, and weep: let your laughter be turned to mourning, and your joy to heaviness.
10 Humble yourselves in the sight of the Lord, and he shall lift you up.

James 4:8 - 10 (Emphasis mine)

Once again, we see the call to "humble ourselves in the sight of the Lord..."  (v 10)  To truly repent, we must feel the sorrow deep in our soul.  We must ache for this sins we have committed.  We must want to obtain the forgiveness and mercy of God with all our soul.  Again, just being sorry isn't enough.

How important is humility? The scriptures tell us:

8  He hath shewed thee, O man, what is good; and what doth the LORD require of thee, but to do justly, and to love mercy, and to walk humbly with thy God?

Micah 6:8

7  But made himself of no reputation, and took upon him the form of a servant, and was made in the likeness of men:
8  And being found in fashion as a man, he humbled himself, and became obedient unto death, even the death of the cross.

Philippians 2:7 - 8

5  Likewise, ye younger, submit yourselves unto the elder.  Yea, all of you be subject one to another, and be clothed with humility: for God resisteth the proud, and giveth grace to the humble.

1 Peter 5:5

(Emphasis in scriptures mine.)

Even the Son of God humbled himself.  In Peter's words, he was "clothed with humility."  What should that teach us?  

Talking about Christ's baptism, Nephi wrote:

5  And now, if the Lamb of God, he being holy, should have need to be baptized by water, to fulfil all righteousness, O then, how much more need have we, being unholy, to be baptized, yea, even by water!

2 Nephi 31:5 (Emphasis mine)

Paraphrasing Nephi, if the Lamb of God have need to humble himself, how much more need have we to humble ourselves?  

Through the atonement, we have the promise that, if we truly humble ourselves, feel great and deep sorrow for our sins, and ask forgiveness of God, we will be able to partake of the mercies offered to us by a merciful God.

It doesn't get any better than this.