Shituf (Hebrew: שִׁתּוּף; also transliterated as shittuf or schituf; literally "association") is a term used in Jewish sources for the worship of God in a manner which Judaism does not deem to be purely monotheistic. The term connotes a theology that is not outright polytheistic, but also should not be seen as purely monotheistic. The term is primarily used in reference to the Christian Trinity by Jewish legal authorities who wish to distinguish Christianity from full-blown polytheism. Though a Jew would be forbidden from maintaining a shituf theology, non-Jews would, in some form, be permitted such a theology without being regarded as idolaters by Jews. That said, whether Christianity is shituf or formal polytheism remains a debate in Jewish philosophy.
Shituf is first mentioned in the commentary of Tosafot on the Babylonian Talmud, in a passage concluding with a lenient ruling regarding non-Jews. Later authorities are divided between those who view Tosfot as permitting non-Jews to swear by the name of God even if they associate other deities with that name, and those who view Tosfot as permitting non-Jews to actually worship such deities.
Though shituf is primarily used as a means of determining how to relate to Christians, it is applied to other religions as well. It is frequently used as a reason to justify interfaith dialogue with Christians.