Heretics are they, who maintain stubbornly against the plain light of truth, any doctrine which overthrows directly, or by necessary consequence the fundamentals of Christian faith.
I. Not every Error makes an Heretic.
For either there is an error against the foundation; as that of the Arians and Marcionites, of whom, they denied the divinity of Christ, these his humanity: Or about the foundation; so the Papists err, while they teach Transubstantiation, on which overthrows the truth of Christ’s humanity: Or besides the foundation; such errors are by Paul compared to hay, wood, &c. 1 Cor. 3. 12.
II. An Heretic is made, 1. by an error in, or about the foundation, 2. by conviction, 3. by contumacy.
III. Not every Schismatic is an Heretic.
He is a Schismatic, who without hurting the foundation of Faith, departs from some Ceremony of the Church, proudly and out of ambition.
Johannes Wollebius, The Abridgment of Christian Divinity, trans. Alexander Ross (3rd edn, London: Joseph Nevill, 1660), pp 232-33.