Alternative Judaism refers to a variety of groups whose members, while identifying as Jews in some fashion, nevertheless do not practice Rabbinic Judaism.^{[citation needed]}

Generally, beliefs of these groups are not compatible with mainstream Judaism. Instead, their beliefs fall outside of the traditional views of the Torah and Jewish law. These movements may be explicitly atheistic, or they may incorporate certain elements foreign to Judaism, such as pagan or other religious traditions. Mainstream Jewish movements often criticize alternative groups as “not being Jewish”, as alternative groups often follow ideas that fall outside two important parameters historically apparent in Jewish theology: the oneness of God and God’s non-corporeal nature.

Alternative forms of Judaism are nothing new in Jewish history, and have appeared in the past in such forms as the Sabbateans and Frankists which fell outside the common Orthodox and Non-Orthodox (Reform, Conservative, Reconstructionist) classification of the four major streams of today's Jewish denominations. These may be combinations of secular Jewish culture and Jewish symbolism with non-Jewish religions and philosophies.