Fundamentalism refers to a belief in a strict adherence to a set of basic principles (often religious in nature), sometimes as a reaction to perceived doctrinal compromises with modern social and political life.
Fundamentalism is a movement through which the adherents attempt to rescue religious identity from absorption into modern, Western culture, where this absorption appears to the enclave to have made irreversible progress in the wider religious community, necessitating the assertion of a separate identity based upon the fundamental or founding principles of the religion.
This formation of a separate identity is deemed necessary due to a perception that the religious community has surrendered its ability to define itself in religious terms. The "fundamentals" of the religion have been jettisoned by neglect, lost through compromise and inattention, so that the general religious community's explanation of itself appears to the separatist to be in terms that are completely alien and fundamentally hostile to the religion itself.