Wickedness Never Was Happiness

Alma teaches his son that all people will be restored (in the Resurrection) to what they have become based on their desires and actions in this life.  

“Do not suppose, because it has been spoken concerning restoration that ye shall be restored from sin to happiness. Behold, I say unto you, wickedness never was happiness…All men that are in a state of nature, or I would say, in the carnal state, are in the gall of bitterness and in the bonds of iniquity; they are without God in the world, and they have gone contrary to the nature of God; therefore, they are in a state contrary to the nature of happiness. And now behold, is the meaning of the word restoration to take a thing of a natural state and place it in an unnatural state, or to place it in a state opposite to its nature? O, my son, this is not the case; but the meaning of the word restoration is to bring back again evil for evil, or carnal for carnal, or devilish for devilish—good for that which is good; righteous for that which is righteous; just for that which is just; merciful for that which is merciful.” (Alma 41:10-13)

Questions:

-Why will Christ save souls from their sins but will not save them in their sins (see previous post entitled Ye Cannot Be Saved in Your Sins)?

-How can one be helped by Christ to move away from his or her sins through repentance so that his or her nature changes toward what is good, righteous, and just?