Andrew, your understanding of Mormonism is flawed.
Latter Day Saints believe in God the Father as being the creator of the heavens and Earth and worlds without end. They believe Christ to be the spiritual and only begotten son and that every human is also a spiritual child of God the Father. Christ is their spiritual brother who they believe attoned for all mankind’s sins providing a way for sin to be forgiven through him.
Latter Day Saints do not worship any other God besides God the Father. They follow the New Testament as that is the doctorine of Christ which replaced the old ways of the Old Testament. After all, people are no longer being stoned to death for leaving their house on the Sabbath. The rules changed a bit after the implementation of the New Testament.
When Latter Day Saints pray they always do so to God the Father through Christ’s name.
“Dear Heavenly Father, we thank you for…blah blah blah…we ask for your understanding and forgiveness for…blah blah blah…we say these things in the name of your son Jesus Christ, amen.”
Clearly they are praying to only one God.
However, that does not mean there are no other God’s in existence. God the Father himself said he is a jealous God and commands that mankind not place any other God before him.
So one needs to define God. What exactly is a God? In the purest, simplest sense, God is a creator. The ultimate creator if you will. No other being that we know of can claim that title. A false God would be someone or something claiming that title or claiming ownership over mankind. People create their own Gods to worship. Praying to anyone but God the Father could be viewed as praying to someone not in charge…not the one true God. Hence why it’s a bit odd that Catholics pray to saints. That is idol worshipping in a way in my opinion.
If God is the ultimate creator and we are all his Children, then there is the possibility that we can learn to be like him. That is what Latter Day Saints believe. That, as spiritual children of God, we have the potential to learn his wisdom. That through the eternities (afterlife) we will continue to learn and grow spiritually on a constant mission for ultimate perfection. If you reach that goal then one becomes Godlike…not replacing the Father but in the likeness of the Father.
Latter Day Saints carry on the biblical tradition of prophets, seers and revelators. They believe prophets are still being called upon by God the Father and his Son through the Holy Spirit to help maintain and guide the church. Prophets even continued after Christ in the New Testament. One could argue that the apostles all were prophets. They believe in a living God, not one who no longer communicates through prophets, but one who did and continues to do so. Why would God stop doing that?
The other doctorine Latter Day Saints believe in is in addition to the Old and New Testaments. The Book of Mormon, Doctorine and Covenants and The Pearl of Great Price do not replace anything. They are a continuation of scripture.
The Bible was not written by one person at one time. It is a collection of writings from various people written over a vast expanse of time that were combined into one book. Stuff was left out, hand picked by man and translated numerous times. All of the versions have discrepancies with each other in slight ways and some major ways. That is one reason why Latter Day Saints believe God the Father continues to call on prophets to lead to help clear up the discrepancies and prevent things from getting mucked up any further.
In the grand scheme of things, if there is indeed a supreme being who we owe alegenience to, I highly doubt this being (God) would really care who calls themselves Christian or not. I think he would be wise enough to see past that and look at actions instead. If one claims to be Christian, it means they are followers of Christ and as such would be striving to be Christlike in all that they do. That, in my book, is a Christian. So yeah, is a Latter Day Saint a Christian? If they are following Christ’s teachings, then yeah, sure they are.