This is also unfortunately a classic definition of religion in general, and thus by itself gives us no way to differentiate between a "religion" and a "cult."
Of course, the traditional definition is that my beliefs are a religion, and yours are a cult.
Which is why it's futile to lable something a religion or cult. In reality, the phrase 'Islam' is just an identifier for a philosophy that is antithetical to the West.
We didn't need to know why the Japanese/Nazis hated us during WWII, and we certainly didn't care whether or not their religions (Shinto/Pagan) were cults.