Social and political roles
Overt syncretism in folk belief may show cultural acceptance of an alien or previous tradition, but the "other" cult may survive or infiltrate without authorized syncresis nevertheless. For example, some Conversos developed a sort of cult for martyr-victims of the Spanish Inquisition, thus incorporating elements of Catholicism while resisting it.
The Kushite kings who ruled Upper Egypt for approximately one century and the whole of Egypt for approximately 57 years, from 721 to 664 BC, constituting the Twenty-fifth Dynasty in Manetho’s Aegyptiaca, developed a syncretic worship identifying their own god Dedun with the Egyptian Osiris. They maintained this worship even after being driven out of Egypt. A temple dedicated to this syncretic god, built by the Kushite ruler Atlanersa, was unearthed at Jebel Barkal.
Syncretism was common during the Hellenistic period, with rulers regularly identifying local deities in various parts of their domains with the relevant god or goddess of the Greek Pantheon, as a means of increasing the cohesion of the Kingdom. This practice was accepted in most locations, but vehemently rejected by the Jews who considered the identification of Yahwe with the Greek Zeus as the worst of blasphemy. The Roman Empire continued this practice, first by the identification of traditional Roman deities with Greek ones, producing a single Graeco-Roman Pantheon, and then identifying members of that pantheon with the local deities of various Roman provinces. Allegedly, an undeclared form of syncretism was the transfer of many attributes of the goddess Isis - whose worship was widespread in the Later Roman Empire - to the Christian Virgin Mary. Some religious movements have embraced overt syncretism, such as the case of melding Shintō beliefs into Buddhism or the supposed amalgamation of Germanic and Celtic pagan views into Christianity during its spread into Gaul, the British Isles, Germany, and Scandinavia. In later times, Christian missionaries in North America identified Manitou - the spiritual and fundamental life force in the traditional beliefs of the Algonquian groups - with the God of Christianity. Similar identifications were made by missionaries at other locations in the Americas and Africa, whenever encountering a local belief in a Supreme God or Supreme Spirit of some kind.
Indian influences are seen in the practice of Shi'i Islam in Trinidad. Others have strongly rejected it as devaluing and compromising precious and genuine distinctions; examples of this include post-Exile Second Temple Judaism, Islam, and most of Protestant Christianity.
Syncretism tends to facilitate coexistence and unity between otherwise different cultures and world-views (intercultural competence), a factor that has recommended it to rulers of multi-ethnic realms. Conversely, the rejection of syncretism, usually in the name of "piety" and "orthodoxy", may help to generate, bolster or authenticate a sense of un-compromised cultural unity in a well-defined minority or majority.