Cults & Heresy

The Reformed orthodox in connection with the idea of fundamental articles, note three kinds of doctrinal error:

(1) errors directly against a fundamental article (contra fundamentum)
(2) errors around a fundamental or in indirect contradiction to it (circa fundamentum)
(3) errors beyond a fundamental article (praeter fundamentum)
The first kind of error is a direct attack–such as those launched by the Socinians–against the divinity of Christ or the Trinity. The second is not a direct negation or an antithesis but rather an indirect or secondary error ultimately subversive of a fundamental–such as a belief in God that refuses to acknowledge his providence. The third category of error does not address fundamental articles directly or indirectly but rather involves faith in problematic and curious questions (quaestiones problematicas et curiosas) that do not arise out of the revealed Word–hay and stubble!–and that, because of their curiosity and vanity, constitute diversions from and impediments to salvation.
Richard Muller, Post Reformation Reformed Dogmatics Vol. 1:Prolegomena to Theology, p. 422-3

“I am not permitted to let my love be so merciful as to tolerate and endure false doctrine. When faith and doctrine are concerned and endangered, neither love nor patience are in order…when these are concerned, neither toleration nor mercy are in order, but only anger, dispute, and destruction – to be sure, only with the Word of God as our weapon.”
– Martin Luther

“Compare Scripture with Scripture. False doctrines, like false witnesses, agree not among themselves.”
-William Gurnall