Religious-philosophical category positing two ultimate principles as eternal and irreducible. The principal historic forms include: (1) Zoroastrianism (the religion of Zoroaster / Zarathustra, c. 600 BC, founded in ancient Persia; teaches the cosmic conflict between Ahura Mazda, the principle of Light and Truth, and Ahriman / Angra Mainyu, the principle of Darkness and Lie); (2) Gnosticism (the broader category of late-antique religious-philosophical systems often positing a dualism between the high spiritual principle and the inferior demiurgic creator of matter); (3) Manichaeism (Mani's third-century AD synthesis of dualist elements, the most thoroughly dualist of the historic religions); (4) Medieval Catharism / Albigensianism (a substantially Manichaean revival in 11th-13th-century Languedoc and northern Italy); (5) Various modern philosophical-spiritualist dualisms (treating matter and spirit as ontologically distinct principles, often with spirit privileged and matter denigrated). The Christian orthodox response is creation ex nihilo: one God creates all things, including matter, all of which He pronounces good (Genesis 1; John 1:3, all things were made by him; and without him was not any thing made that was made; Colossians 1:16-17). Evil is not an eternal co-principle with God but a creaturely defection from God's good creation; matter is not the product of an evil principle but the good creation of the one God. The Reformed-confessional tradition (Westminster Confession IV.1; Heidelberg Q. 26) maintains creation ex nihilo and the goodness of created matter against all dualist religious positions. The patriarchal-Reformed reader engages religious dualism with the substantive orthodox doctrine of creation as the refutation.