First of all, however, we need to ask the very important question, what do we mean by a cult? The website Cultwatch has a helpful couple of definitions of the word. The first is the 'Modern' definition of a cult, that is the meaning of the word as it is understood in our culture.
"The modern definition of "Cult" refers to any group that uses manipulative psychological “Mind Control” techniques to recruit and control their members"
The second definition is the older one that is generally intended when people call Mormonism a cult:
"The historical definition of a cult is any group, which claims to be a Christian group yet teaches something that is not primarily a Christian belief."
Clearly we have to be careful what we mean by a cult, but also how that word is understood by other people. I would suggest that most people outside of conservative evangelical churches are operating with what Cultwatch calls "the modern definition."
Now, Mormonism is certainly a 'cult' according to the "historical definition", it is a religious group that claims to be Christian but whose teachings are in contradiction to historic Christian beliefs, a claim that I hope to show to be true in future posts. It is certainly not a cult by the 'modern definition'. While early Mormonism certainly exercised a great degree of control over its members, modern Mormonism (by which I mean the Church of Jesus Christ of Latter-Day Saints) does not. There are liberal Mormons who acknowledge that the Book of Mormon was written by Joseph Smith and was not translated from any gold plates; and these liberal Mormons are still members in good standing of the LDS church and teachers - a thing that no cult according to the modern definition could do. Thus we should not call Mormonism a cult to those whose primary or only understanding of the word is the modern definition, because it would lead to misunderstanding, and gives the impression that we are saying things about Mormonism that are not true.
Before the reader is tempted to anathematize me, let me re-iterate, according to the historical definition, it is a cult. It is a non-Christian religion that uses Christian terminology. If you like, it is a Christian deviation. The core beliefs of Mormonism are utterly inconsistent with the teachings of historic Christianity, and this is why we cannot accept Mormons as Christians.
God willing, I shall start addressing the reason I say this in the next post.
[Please note that I am addressing only the beliefs of the Church of Jesus Christ of Latter-Day Saints, not any Mormon splinter groups such as the Community of Christ (formerly the RLDS), the Church of Jesus Christ of Latter-Day Israel, or the Church of Jesus Christ Restored 1830]