syncretism
Syncretism (noun) means the blending together of different beliefs or systems, such as religious or cultural ones, into one.
Etymology
Comes from Latin syncretismus, which came from Ancient Greek συγκρητισμός (sunkrētismós, "federation of Cretan cities"), from συγκρητίζω (sunkrētízō, "to unite against a common enemy"), from σύν (sún, "together") (see English syn-) plus Κρῆτες (Krêtes, "Cretans"). On the surface it looks like syn- + Crete + -ism ("Crete joining together").