Mormonism is not Christian maybe you should actually look into the cult.
______________________________________________________
I suspect I know more about the Mormons than most people although there are likely Mormons who know more than me.
If you define “Christian” as one who follows the Nicean Creed or what most now call The Apostles Creed then no, Mormons are emphatically not Christian, but I don’t think that is a good definition even though perhaps most people think of that when they think “Christian”. I do not. In my mind anyone who tries to follow Christ and His teachings is Christian. If you follow the Nicean Creed then you are either one of the several “Catholic” churches or one of it's offshoots, Protestant if you will. I personally don't believe that the Nicean Creed really defines Christianity very well. I'm not saying there is something wrong with it but it really was created to put up a fence around a particular view of Christianity. I won't go into great detail here, I likely have in the past but I'm on vacation so will just touch the subject lightly. In 325 AD when the Emperor of Rome, Constantine, who was the head of a Non Christian Church called all the Christian Bishops to a meeting in Nicea he did it to define what Christianity was and was not. He allowed the different Bishops to present their definitions and decided on one in particular as what would be the legal Christianity. The Bishop who presented the winning plan was from Greece and had an ally from Egypt. The ally from Egypt was actually Greek but was living in Alexandria where he had a very large church and was a close friend of Constantine.
This “Eastern” view of Christianity was not accepted by approximately 1/3rd of those in attendance and they were threatened with expulsion, excommunication even death if they did not sign on, still very many didn't. Constantine relented and said they could still call their churches Christian and be a part of the now universal or “catholic” church without signing on to the Nicean Creed. The only part of this creed that was not acceptable was the definition of the “Holy Trinity”. For another 60 years there was division in The Church about the Trinity until another council was held in 385. After that it was mandatory to believe in the “Creed” to be Christian and to refuse could mean death, especially if you were a Church leader.
Today in the “Universal” Church we have a Pope, someone who is the senior bishop to all the others, he is considered “infallible” in his proclamations about Church doctrines. He occupies the same position as Peter did in the Early Church according to the Universal church as an Apostle of Jesus Christ.
Now to the point. In the Universal church or Catholic church specifically The Roman Catholic Church there has since it's beginning been a definition of who was in the universal church and who was not. If you said you believed in the Creed then you were else you were not. Believing in the creed did not make you Christian but made you part of the “Universal” or Catholic church. There have always been Christian churches that were not a part of this “Catholic” church and their differences were varied.
Eventually the Romans and Popes killed off most of the leaders of these non conforming churches although some still exist there are only a few left. I put Mormons in the same category as the non conforming early Christian churches. They are not part of the “Universal” church but are still most definitely Christian.
In the letters or epistles we have from the Apostle Paul we hear of him rebuking the several organized churches for their waywardness. The several churches without an Apostle in their presence would tend to fall away from the pure worship of Christ ascribed by the early church leaders and kept bringing other doctrines in. Although the churches taught many things that Paul condemned they were still considered Christian churches.
If you ever investigate the Mormons you will find that they are Christian. They worship The Son of God as The Savior of mankind. They worship His Father as God. They do not believe that Christ is The Father, they do however believe that He is the God of the Old Testament, that He is in fact Jehovah. that is in fact what nearly broke the universal church apart before it even got started in 325AD. there is no one alive or in holy writ save a very few who have claimed to see God The Father. There is really only one that I know of and that is the Martyr, Stephen. In his description of what he saw while being stoned to death for being a Christian he claimed he saw Jesus and God standing side by side. While John The Baptist never claimed to see God he did claim that there was a voice from Heaven testifying that Jesus was His Son.
I'm not trying to make an argument for the Mormon view of The Trinity only saying that there is plenty of room for acceptance of their view scripturally.
Mormons have a prophet who claims to be an ordained Apostle of Jesus Christ. The Roman Catholic Church makes a similar claim. While Roman Catholics don't call their Apostle a Prophet, apostles are by definition prophets. Really not much different than the Mormons except that the Catholics claim that their first Apostle was ordained by Christ in mortality and the line continues unbroken today. There are many who dispute this claim but, anybody can dispute anything. There is nobody forcing anybody to accept the Nicean Creed today. Unlike believers of Islam Christian can believe what they want and still claim to be Christians without having themselves crucified or losing their heads.
The Mormon churches in the area around my wifes church belong to a local group of “Christian” churches who perform humanitarian service to those in need. When this council of churches allowed the Mormons to start being a member a leader of one of the group of churches complained about it saying they weren't Christian. they asked the representative to summarize their beliefs and the council decided that they were indeed Christian and they became a member of the group.
I'm not sure why one person who says they are Christian would have so much animus with someone else who said he was a Christian but personally I think that anyone who really tries to follow Jesus Christ is a Christian. All churches probably have some baggage we would rather they left behind but I don't think it affects their being Christian.