Totalism is to philosophy (including religion, ideology, & other belief-systems) what totalitarianism is to political science (government & politics). It mandates only one way for all and seeks to totally control all aspects of a person's life. Many infamous religious cults and "new religions" are totalist, as well as some older religions, or imitations of religions, such as Christianism and Islamism. Ironically, a totalist belief system will refer to all other belief systems as cults (using the word "cult" to mean "any and all deviation from the 'One True Way'), when in fact, all totalist belief systems themselves are really cults in the scientific sense.
However, not all new religions are totalist or cults. In fact, most paths associated with the New Age movement are mostly or wholely the opposite of totalism and onlyism, and, while New Agers are usually open to hearing what onlyist cults have to say and are even eager to try to incorporate or make use of their better points, they are mostly saddened when followers of such belief systems seek to shut everything else out and to hate or even be aggressively hostile to everyone else.