Inclusivism is one of several approaches in religious studies, anthropology, or civics to understand the relationship between different religions, societies, cultures, political factions etc. It asserts that there is beauty in the variety of different schools of thoughts, and that they can live together in harmony. It stands in contrast to exclusivism, which asserts that only one way is true and all others are erroneous.
Within religious studies and theology, inclusivism is the belief that, although only one belief system is true, aspects of its truth can be found in other religions. This is contrasted from religious pluralism, which asserts that all beliefs are equally valid within a believer's particular context.
Broadly speaking, there are two schools of Inclusivist thought:
Relativistic inclusivism, which asserts that the believer's own views are true only in their particular context, and believers of other traditions have their own validity.
Absolutist inclusivism, which asserts that an unknown set of assertions are Absolutely True, that no human being currently living has yet ascertained absolute truth, but that all human beings have partially ascertained absolute truth.
Interpretatio graeca was the tendency of ancient Greek writers to equate foreign divinities to members of their own pantheon. Herodotus, for example, refers to the ancient Egyptian gods Amon, Osiris, and Ptah as "Zeus," "Dionysus," and "Hephaestus." This could be seen an example of inclusivism, as could syncretism.
Syncretism functioned as an essential feature of Ancient Greek religion. Later on, Hellenism, a consequence of Alexander the Great's belief that he was the son of a god, reinforced by the Oracle of Zeus-Ammon at Siwa in Egypt, itself showed syncretic features, essentially blending Persian, Anatolian, Egyptian (and eventually Etruscan-Roman) elements within Hellenic formulations. After the Hellenization of the Egyptian culture initiated by Ptolemy I Soter, Isis became known as "Queen of Heaven" and worshipped in many aspects and by many names besides that of Hera.