The Real Turretin on: Validity of Baptisms by Heretics

Turrettin, vol. iii. p. 442. "Some heretics," he says, "corrupt the very substance of baptism, as the ancient Arians, modern Socinians, rejecting the doctrine of the Trinity others, retaining the essentials of the ordinance and the true doctrine of the Trinity, err as to other doctrines, as formerly the Novatians and Donatists, and now the Papists and Arminians. The baptisms of the former class are to be rejected; those of the latter are retained, although they err as to many doctrines, and their baptisms, in circumstantials, are polluted by various ceremonies." See also Pictet, La Theologie Chretienne, Lib. xv. c. 13.

(source - C. Hodge, The Church and Its Polity - p. 194)

-Turretinfan