In the temple we are told that Adam and Eve were sent out into the world to learn from their own experiences discernment between good and evil. Their experience in the garden and with Lucifer shows that in their innocence they had not gained that discernment.
Knowing Good from Evil is discussed a lot in the scriptures.
Alma 13:13
Moses 6:55
Alma 29:5
Moses 4:11
Helaman 14:30-31
Abraham 5:9
Moses 4:28***
Moses 3:17
2 Ne 2:18
Alma 42:3
Alma 42:7
Moses 5:11
1 Kings 3:9
Genesis 3:5***
Genesis 2:9
Genesis 3:22***
Those with *** state that Adam and Eve knowing good and evil would make them as the Gods.
From the perspective of knowing good from evil being the task of mortality, Moroni's exortations in his final words increase their importance. He is telling us how to discern good from bad so our mortality will be successful.
The commandments tell us what is good. Keeping on the covenant path keeps us choosing to good -- which is the point of being able to discern it. This is stated in Moroni 10:30: Hold to the good gifts, touch not the evil gifts nor unclean things.
Moroni 10 Exortations Summary
1 3 Remember How Good God Has Been to People/Ponder It
2 4 Ask if This is True; Holy Ghost Answers
3 7 Deny Not the Power of God
4 8 Deny Not the Gifts of God
5 18 Remember Good Gifts are from God
6 19 God is the Same; Loss of Gifts is From Unbelief of Men
7 27 Remember b/c You'll be Asked
8 30 Come Unto Christ; Hold Good Gifts; Touch Not Evil Gifts
My Exortation Notes in Moroni
3 Remember/Ponder
I would exhort you that when ye shall read these things, if it be wisdom in God that ye should read them, that ye would remember how merciful the Lord hath been unto the children of men, from the creation of Adam even down until the time that ye shall receive these things, and ponder it in your hearts.
First Exhort:
Remember the Lord's mercy,
Read this and
Ponder these things in your heart.
4 Ask if True; Holy Ghost Answers
...I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost.
Second Exhort:
Ask God if they are true. The Holy Ghost is the way you will know if they are true.
Additional information to discern if this is from God: Good things come from God and acknowledgeth he is.
7 Deny Not the Power of God
...I would exhort you that ye deny not the power of God; for he worketh by power, according to the faith of the children of men, the same today and tomorrow, and forever.
3rd Exhort
Third Exhort:
Do not deny the power of God and the Holy Ghost, which will witness to you that Christ is.
Our level of faith determines how much we experience the power of God in our lives.
8 Deny Not the Gifts of God
And again, I exhort you, my brethren, that ye deny not the gifts of God, for they are many; and they come from the same God. And there are different ways that these gifts are administered; but it is the same God who worketh all in all;
4th Exhort
Fourth Exhort:
Do not deny the gifts of God.
18 Remember Good Gifts are from God
And I would exhort you, my beloved brethren, that ye remember that every good gift cometh of Christ.
5th Exhort
Fifth Exhort:
Remember that every good gift comes from God.
19 God is the Same; Loss of Gifts is From Unbelief of Men
And I would exhort you, my beloved brethren, that ye remember that he is the same yesterday, today, and forever, and that all these gifts of which I have spoken, which are spiritual, never will be done away, even as long as the world shall stand, only according to the unbelief of the children of men.
Sixth Exhort:
Remember God is the same always. These gifts are spiritual and our faith is required for them to be given to us. If there are no good gifts, it is because we have no faith.
27 Remember b/c You'll be Asked
27 And I exhort you to remember these things; for the time speedily cometh that ye shall know that I lie not, for ye shall see me at the bar of God; and the Lord God will say unto you: Did I not declare my words unto you, which were written by this man, like as one crying from the dead, yea, even as one speaking out of the dust?
7th Exhort
Seventh Exhort:
Remember these things. (The end comes soon and you will be asked by God 'why didn't you believe what I had this m
30 Come Unto Christ; Hold Good Gifts; Touch Not Evil Gifts
30 And again I would exhort you that ye would come unto Christ, and lay hold upon every good gift, and touch not the evil gift, nor the unclean thing.
8th Exhort
Eighth Exhort:
Come unto Christ.
Hold onto all good things.
Do not (even) touch evil gifts or unclean things.