There are leftist radicals out there for sure, brainless. But how are they fundamentalists?
In comparative religion, fundamentalism has come to refer to several different understandings of religious thought and practice, including literal interpretation of sacred texts such as the Bible or the Qu'ran and sometimes also anti-modernist movements in various religions.
Although fundamentalism is a continuing historical phenomenon, illustrated by the creation of the Sikh Khalsa Panth in 1699, it is increasingly a modern phenomenon, characterized by a sense of embattled alienation in the midst of the surrounding culture, even where the culture may be nominally influenced by the adherents' religion. The term can also refer specifically to the belief that one's religious texts are infallible and historically accurate, despite possible contradiction of these claims by modern scholarship.