Most ancient Greek gods have a Roman match and a Latin name. Many Roman gods have a match in the Germanic pantheon.
The Greek Zeus is the Roman Jupiter and the Germanic Thor.
When cultures collide with each other, the familiar is disrupted by the unknown. The unfamiliar is forced into the family through an act of ‘interpretatio‘.
The interpretatio romana equates foreign deities with gods in the Roman pantheon. This makes it easier for Roman writers to present the foreign as less foreign, as a kind of close-to-home item. It promotes universalism. The ancient Greeks had done the same –interpretatio graeca-, and Germanic authors, like the Anglo-Saxon writers, likewise later on – interpretatio germanica.
The interpretatio may be a literary device used by authors confronted with the reality of a foreign culture, but it is also something we do today, more prosaically but also more commonly. Noodles are a kind of pasta and the Calabrian ‘nduja a kind of salami spread. These are approximations which are somewhat true and somewhat false. They are not substantially different from saying that the fascinatingly elusive god Loki is a kind of Mercury who is a kind of Hermes.
There is reason and there is the desire for rationality, which is the desire to establish order in the midst of randomness. Rendering the strange familiar or at least making it feel related is an important feature of human culture. As we realise that more and more things are interrelated, and that cultures are never as clearly demarcated from one another as we would think, we shall practice interpretatio at an increasingly larger scale.