The Latter day Saint Nature of God vs. the Evangelical Nature of God:

Latter-day Saints believe: "As man is, God once was, as God is, man may become." This can be broken down and explained as follows:

As man is, God once was: Jesus is God and lived on the Earth as a mortal man.

As God is, man may become: Jesus was resurrected and now lives as an immortal in Heaven. Someday man will be resurrected and may live immortally in Heaven.

The difference between evangelicals and latter-day saints is not the fact that we will be one with God as immortal beings (gods) like Jesus or that Jesus lived on earth as a man.

If you believe these scriptures, it is very difficult to refute:

 "Be ye therefore perfect, even as your Father which is in heaven is perfect. (Matthew 5:48)"

"Is it not written in your law, I said, Ye are gods? If he called them gods, unto whom the word of God came (and the scripture cannot be broken), say ye of him, whom the Father sanctified and sent into the world, Thou blasphemest; because I said, I am the Son of God?" (John. 10:34-36).

"That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me." (John 17:21)

"And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together." (Romans 8:17)

"Then answered Jesus and said unto them, Verily, verily, I say unto you, The Son can do nothing of himself, but what he seeth the Father do: for what things soever he doeth, these also doeth the Son likewise." (John 5:19)

The criticized difference between latter-day saints and evangelicals comes from what latter-day saints believe will happen in heaven over eternity.  The LDS church has some revelation and a lot of speculation about immortality in heaven over the duration of eternity.

However, the real difference doesn't have its origin in this difference, but in something else.

Latter-day saint beliefs about what will happen in heaven over the course of eternity is connected to their belief in the nature of God—which is different than evangelicals.

Latter-day saints believe that God is their literal spiritual Father and that we are created in His image. They believe that mankind is the same kind of "species" as God, but in an extremely, incomprehensively less developed state (somewhat like an embryo). In other words, latter-day saints take the name "Father in Heaven" and "children of God" literally.

Evangelicals believe that the scripture that says that we are created in Gods image isn't saying that man looks like God in a physical sense. They don't believe that we are "children of God" in a literal sense. And they don't believe the scriptures that say that God is our spiritual "Father" is speaking in a literal way.

If the literal interpretations of these scriptures are used, then it is logical to assume that we will be like God, our literal Father and the latter-day saint perspective would be the most reasonable assumption as to what occurs in Heaven over the course of eternity as an immortal being.

However if the scriptures that speak about God being our Father and us as His children are not speaking in a literal sense, then the evangelical perspective about what occurs in heaven over eternity would be more reasonable. And that is: "we have almost absolutely no idea—but it's good"

Ultimately we just have a different idea about what it would mean to become "as He is". All the following assumptions are reasonable.