It is stronger than that. Mormonism is not just comparable to Protestantism. Moromonism is PART of Protestantism. Protestantism consists of Baptists, Lutherans, Anglicans, Metholidist - AND ALSO Unitarians, Jehovah Witnesses, and Mormonism.
I think if you analyze the definition of Protestantant, you would see that Mormons would be Protestant. Here are the possible definitions of a Protestant.
- A Protestant is one who adheres to the tenets of the Reformers in the Reformation.
This cannot be the definition, because Arminians who believe in free will would disagree with the Reformers. By this definition, Arminian could not be Protestants. Also, the reformers taught infant baptism. This would mean Baptists are not Protestants.
- A Protestant is one who believes in sola scriptura.
This cannot be the definition, either. There are many liberal Protestants who do not believe in scripture at all. They may not be Christian, but they are still considered Protestants even by conservative Protestants. Also, Jehovah Witnesses believe in sola scriptura.
- A Protestant is one who professes to be a Christian but not a Catholic.
This is the definition that fits.“Protestant” comes from the word “to protest”. We could devote a whole topic on what in particularly they were protesting, but I think there is a general agreement that it had something to with the Catholic Church. So Protestant is more defined in the negative, it is someone in some way protesting against the Catholic Church.
This fits the Mormons. They consider themselves to be Christians and they consider the Catholic Church corrupting the gospel. In fact, all Protestants, whether they be conservative or liberal. Whether they be Anglican or Baptist. Whether they be charismatic or fundementalist. There is only one thing they all agree on - they agree that the Catholic Church corrupted the original teachings of Jesus and the apostles.
There is no such thing as Protestant theology. There is no unified system of beliefs that all Protestants agree on - except that the Catholc Church corrupted the message of Jesus. Since Mormons would believe this, they are Protestant.