Doctrine and Covenants 19: 1-12;

 

Why is it important for you to know the eternal nature of God?

"Revelation given through Joseph Smith, at Manchester, New York, likely in the summer of 1829. In his history, the Prophet introduces it as “a commandment of God and not of man, to Martin Harris, given by him who is Eternal.”

1–3, Christ has all power; 4–5, All men must repent or suffer; 6–12, Eternal punishment is God’s punishment; 13–20, Christ suffered for all, that they might not suffer if they would repent; 21–28, Preach the gospel of repentance; 29–41, Declare glad tidings.

1 I am Alpha and Omega, Christ the Lord; yea, even I am he, the beginning and the end, the Redeemer of the world.

2 I, having accomplished and finished the will of him whose I am, even the Father, concerning me—having done this that I might subdue all things unto myself—

3 Retaining all power, even to the destroying of Satan and his works at the end of the world, and the last great day of judgment, which I shall pass upon the inhabitants thereof, judging every man according to his works and the deeds which he hath done.

4 And surely every man must repent or suffer, for I, God, am endless.

5 Wherefore, I revoke not the judgments which I shall pass, but woes shall go forth, weeping, wailing and gnashing of teeth, yea, to those who are found on my left hand.

6 Nevertheless, it is not written that there shall be no end to this torment, but it is written endless torment.

7 Again, it is written eternal damnation; wherefore it is more express than other scriptures, that it might work upon the hearts of the children of men, altogether for my name’s glory.

8 Wherefore, I will explain unto you this mystery, for it is meet unto you to know even as mine apostles.

9 I speak unto you that are chosen in this thing, even as one, that you may enter into my rest.

10 For, behold, the mystery of godliness, how great is it! For, behold, I am endless, and the punishment which is given from my hand is endless punishment, for Endless is my name. Wherefore—

11 Eternal punishment is God’s punishment.

12 Endless punishment is God’s punishment." (Doctrine and Covenants 19: 1-12)

And here's the commentary entitled: “I, God, am endless.” : 

"Joseph Smith explained that the revelation in section 19 is “a commandment … to Martin Harris, given by him who is Eternal” (section heading). Look for places in verses 1–12 where the Lord emphasizes His eternal nature. Why do you think it was important for Martin Harris to know this about the Lord? Why is it important for you to know it?

Why do you think Jesus Christ is called “the beginning and the end”? (verse 1)."

It's important for Martin Harris to know the Lord's eternal nature to assure him that God's work in which he was helping to move forward is eternal. He was helping to accomplish God's work as he sacrificed his own property for the printing of the Book of Mormon. Despite the uncertainty that he would be able to continue to own his property after getting it mortgaged, Martin could rest assured that everything would be all right as he relied more on the Lord and put in God's hands what's gonna happen next to his property. 

It's important to me to know the Lord's eternal nature to assure myself that as I continue to put God first in my life, relying on Him for my support as I strive to do what I can to reach my goals especially financially, everything will fall in its proper order. He knows exactly what I need and He is showering me the exact blessings that I need at the time that I need them the most. 

Jesus Christ is called "the beginning and the end" because He was chosen by Heavenly Father in the beginning when God's plan was presented to His children to be sent here on earth and do the will of the Father to accomplish His work for His children and He is called to complete the work in the end as well as all of God's children will be accountable to Him and face Him to be judged whether they have proven themselves worthy to return to Heavenly Father's presence or not.