Syncretism's popular origin story about quarrelling Cretans is probably false
Plutarch claimed syncretism meant Cretans burying their feuds to face a common enemy. The etymology is almost certainly wrong, yet the idea stuck. Blending faiths has produced new gods, an emperor's personal religion and bitter accusations of corrupting pure truth, and some scholars argue every religion is a blend anyway.
Syncretism is the merging of separate beliefs, most often religious ones, into a single integrated system. It differs from eclecticism, which picks and chooses elements while keeping them distinct. The Oxford English Dictionary first records the English word in 1618. Plutarch, writing in the 1st century, explained the Greek original as a union of Cretans who reconciled when outsiders threatened; modern etymologists call that a naive guess and prefer sun-, with, joined to a verb meaning to mix.
Blending tends to happen where cultures touch. Neighbouring traditions rub off on each other, and conquerors often impose their gods without fully stamping out older rites. Between 721 and 664 BCE the Kushite kings of Egypt's Twenty-fifth Dynasty merged their own god Dedun with Osiris, and kept that worship after they were expelled. In the 16th century the Mughal emperor Akbar launched the Din-i Ilahi, or Divine Faith, drawing mainly on Islam and Hinduism with touches of Christianity, Jainism and Zoroastrianism; it looked more like a personality cult than a church.
Mixing can also be quiet resistance. Some conversos venerated victims of the Spanish Inquisition as martyrs, borrowing Catholic forms while pushing back against the Church. States have engineered blends for control, as with the Living Church in Soviet Russia and the German Evangelical Church under the Nazis.
The word carries a charge. Believers in revealed, exclusive faiths, including the Abrahamic religions, often see syncretism as betrayal, since an incompatible addition would make the original untrue. Its neutral, rational sense arguably dates to Diderot's Encyclopédie. Véronique Altglas goes further, arguing that the label implies earlier religions were pure and fixed, when in her view all of them combine many sources. Jerry H. Bentley stresses the upside: syncretism can broker cultural compromise.
Source: Syncretism