The same definitions, with the same caveat, apply equally well to Catholicism, Mormonism or any other major religion. Actually, until a few decades ago the term “cult” did not have the Children of God, Jim Jones or Manson connotations that we think of first today.
If you disagree, please point out the definitions that are not applicable to other major religions.
The only difference I can see is who the people are who regard each religion as “unorthodox or spurious.” If you believe your own religion is true, all those that disagree with or contradict it are more or less by definition false, “unorthodox or spurious” to varying degrees.
I am by no means a fan of Islam, but calling it a cult does not accomplish anything except to irritate its adherents, some of whom might otherwise be willing to work on our side. If we wish to avoid a Holocaust-like resolution of the conflict, we need these people.
Not even Jesus, the Christ avoided calling evil what it was. He called evil by different names.....snakes, vipers, whited sepulchres, hypocrites...by all means more direct words than "cult". Islam will never work on our side, to fix the mess they've created in this world. Regardless of what we do to accomodate them or try to work with them. It is a religious death-loving cult based totally upon utter and complete submission. Not loving and willfull obedience,but by forceful total submission - like a slave. You will either submit and become Muslim, pay jazirya tax, or die. Either you will submit to them, or they will have to be forced to abandon their prime objective. Please don't fall into the trap of thinking you can change their line of thinking through cooperative efforts. They will only interpret your actions as "submission". Just look at their actions toward Israel.