I've decided to focus my critique on their doctrine of God. Specifically, I had in mind the following quote from the King Follett discourse delivered by Joseph Smith. (http://jon.swelter.net/king_follett_discourse.html)
"God himself was once as we are now, and is an exalted man, and sits enthroned in yonder heavens! That is the great secret. If the veil were rent today, and the great God who holds this world in its orbit, and who upholds all worlds and all things by his power, was to make himself visible, -- I say, if you were to see him today, you would see him like a man in form -- like yourselves in all the person, image, and very form as a man; for Adam was created in the very fashion, image and likeness of God, and received instruction from, and walked, talked and conversed with him, as one man talks and communes with another.
In order to understand the subject of the dead, for consolation of those who mourn for the loss of their friends, it is necessary we should understand the character and being of God and how he came to be so; for I am going to tell you how God came to be God. We have imagined and supposed that God was God from all eternity. I will refute that idea, and take away the veil, so that you may see."
Here there is also that little catch-phrase:
"As man is, God once was;and as God is, man may become."
However, I will bring Isaiah chapters 40-48 to bear on this teaching. Here are a list of verses that teach the exact opposite, that there is only one God. There are no other gods. He alone is God from all eternity. He created everything Ex-Nihilo, out of nothing, simply by the power of his Word.
I think the words recorded here are sufficient enough to establish a view of God that is incompatible with the statements of Joseph Smith.
To whom then will you compare me,
that I should be like him? says the Holy One.
Lift up your eyes on high and see:
who created these?
He who brings out their host by number,
calling them all by name,
by the greatness of his might,
and because he is strong in power
not one is missing.
Why do you say, O Jacob,
and speak, O Israel,
"My way is hidden from the LORD,
and my right is disregarded by my God"?
Have you not known? Have you not heard?The LORD is the everlasting God,
the Creator of the ends of the earth.
He does not faint or grow weary;
his understanding is unsearchable. - Isaiah 40:25-28 ESV
Who has performed and done this,
calling the generations from the beginning?
I, the LORD, the first,
and with the last; I am he.- Isaiah 41:4 ESV
Thus says God, the LORD,
who created the heavens and stretched them out,
who spread out the earth and what comes from it,
who gives breath to the people on it
and spirit to those who walk in it:
"I am the LORD; I have called you in righteousness;
I will take you by the hand and keep you;
I will give you as a covenant for the people,
a light for the nations,
to open the eyes that are blind,
to bring out the prisoners from the dungeon,
from the prison those who sit in darkness.
I am the LORD; that is my name;
my glory I give to no other,
nor my praise to carved idols. - Isaiah 42:5-8
"You are my witnesses," declares the LORD,
"and my servant whom I have chosen,
that you may know and believe me
and understand that I am he.
Before me no god was formed,
nor shall there be any after me.
I, I am the LORD,
and besides me there is no savior. - Isaiah 43:10-11 ESV
Thus says the LORD, the King of Israel
and his Redeemer, the LORD of hosts:
"I am the first and I am the last;
besides me there is no god.
Who is like me? Let him proclaim it.
Let him declare and set it before me,
since I appointed an ancient people.
Let them declare what is to come, and what will happen.
Fear not, nor be afraid;
have I not told you from of old and declared it?
And you are my witnesses!
Is there a God besides me?
There is no Rock; I know not any."- Isaiah 44:6-8 ESV
Thus says the LORD, your Redeemer,
who formed you from the womb:
"I am the LORD, who made all things,
who alone stretched out the heavens,
who spread out the earth by myself. - Isaiah 44:24 ESV
I am the LORD, and there is no other,
besides me there is no God;
I equip you, though you do not know me,
that people may know, from the rising of the sun
and from the west, that there is none besides me;
I am the LORD, and there is no other.
I form light and create darkness,
I make well-being and create calamity,
I am the LORD, who does all these things. - Isaiah 45:5-7 ESV
They will plead with you, saying:
'Surely God is in you, and there is no other,
no god besides him.'" - Isaiah 45:14 ESV
For thus says the LORD,who created the heavens
(he is God!),
who formed the earth and made it
(he established it;
he did not create it empty,
he formed it to be inhabited!):
"I am the LORD, and there is no other - Isaiah 45:18 ESV
"Assemble yourselves and come;
draw near together,
you survivors of the nations!
They have no knowledge
who carry about their wooden idols,
and keep on praying to a god
that cannot save.
Declare and present your case;
let them take counsel together!
Who told this long ago?
Who declared it of old?
Was it not I, the LORD?
And there is no other god besides me,
a righteous God and a Savior;
there is none besides me.
"Turn to me and be saved,
all the ends of the earth!
For I am God, and there is no other.
By myself I have sworn;
from my mouth has gone out in righteousness
a word that shall not return:
'To me every knee shall bow,
every tongue shall swear allegiance.' - Isaiah 45:20-23 (Compare with Philipians 3)
Remember this and stand firm,
recall it to mind, you transgressors,
remember the former things of old;
for I am God, and there is no other;
I am God, and there is none like me,
declaring the end from the beginning
and from ancient times things not yet done,
saying, 'My counsel shall stand,
and I will accomplish all my purpose,' - Isaiah 46:8-10 ESV
It should be noted that much of the language here is used of Christ. Notice the frequent "I am he" in Isaiah 40 through 48. Jesus uses this language of himself in John chapter 8. "Unless you believe that I am he you will die in your sins". John 1:3 says that Christ made everything, "and without him was not anything made that was made". Colossians 1:16 says that by him, Jesus, everything was created. Hebrews 1:3 says that the whole universe is upheld by Christ.
Compare these passages above with the testimony of the New Testament about the person and nature of Christ and you will be forced by consitency to confess the Holy Trinity in it's undivided Unity.
Here is an extensive interview on Mormonism with Dr. James White on the Way of the Master show:
Part 1 -
Part 2 -
Part 3 -