Why is God the Father referred to as "Eternal Father" in LDS writings when He is not believed to be eternal? I was recently reading some LDS material and noticed something that did not make sense to me.  As I understand LDS teaching, God the Father was once a man on another planet who attained godhood through how he lived.  Prior to that, He was the spiritual offspring of the god of that world.  Thus, He had a beginning and is not eternal.
However, LDS scripture refers to Him as Eternal Father in many different places, including the following:

O God, the Eternal Father, we ask thee in the name of thy Son, Jesus Christ, to bless and sanctify this wine to the souls of all those who drink of it, that they may do it in remembrance of the blood of thy Son, which was shed for them; that they may witness unto thee, O God, the Eternal Father, that they do always remember him, that they may have his Spirit to be with them. Amen  D&amp;C 20:79
O God, the Eternal Father, we ask thee in the name of thy Son, Jesus Christ, to bless and sanctify this bread to the souls of all those who partake of it; that they may eat in remembrance of the body of thy Son, and witness unto thee, O God, the Eternal Father, that they are willing to take upon them the name of thy Son, and always remember him, and keep his commandments which he hath given them, that they may always have his Spirit to be with them. Amen.  Moroni 4:3
We believe in God, the Eternal Father, and in His Son, Jesus Christ, and in the Holy Ghost. Articles of Faith 1:1

So, my question is why the term &quot;Eternal Father&quot; is used of a being who is not in any way eternal.  What is meant by the world &quot;eternal&quot;?
(For these references, I just searched the lds.org site for &quot;eternal father&quot;.)
This is relatively straightforward. 

From the LDS article on Eternal Life:


  Eternal life is the phrase used in scripture to define the quality of
  life that our Eternal Father lives. The Lord declared, “This is my
  work and my glory—to bring to pass the immortality and eternal life of
  man” (Moses 1:39). Immortality is to live forever as a resurrected
  being.


Think for a moment of a ray and a line.  A ray goes on forever in one direction.  A line goes on forever in both directions. Each has infinite length.

Mainstream Christianity teaches that God is eternal in that He has always existed and will always exist, and LDS theology teaches that he is eternal because he will always exist.

It's a different definition of the term, but not one that's not reasonable from their point of view.  After all, we are promised eternal life as Christians, are we not?