Matrism

Matrism is a monotheistic western Eidoran religion that revolves around the Allmother, the creator of everything. It shares a lot of similarities with Patrism (the two gods stem from the same Proto-religion), but is very distinct in many aspects: for example, the Allmother is seen as the one and only true god, and other "gods" are at best not real, or at worst, some kind of demonic or evil being.

Patrism
Despite originating from the same ancient religion (or maybe precisely because of), Matrism and Patrism have historically had a very strained relationship. At the very least, the similarities are acknowledged and one religion sees the other as a very far-reaching heresy. The disagreements between the two are mostly two-fold: the true identity of the god (Mother? Father? Male or Female?), and the treatment of other gods in relation to it.