“Nor can it be objected here that faith was required also in the first covenant and works are not excluded in the second …. They stand in a far different relation. For in the first covenant, faith was required as a work and a part of the inherent righteousness to which life was promised. But in the second, it is demanded―not as a work on account of which life is given, but as a mere instrument apprehending the righteousness of Christ (on account of which alone salvation is granted to us). In the one, faith was a theological virtue from the strength of nature, terminating on God, the Creator; in the other, faith is an evangelical condition after the manner of supernatural grace, terminating on God, the Redeemer. As to works, they were required in the first as an antecedent condition by way of a cause for acquiring life; but in the second, they are only the subsequent condition as the fruit and effect of the life already acquired.”
Quote in Robert Godfrey’s lecture titled “A Survey of Church History, Part 4 A.D. 1600-1800 Scholastic Theology” starting at 7:25. The lecture is available for free here.
The quote comes from Francis Turretin’s Institutes of Elenctic Theology, Twelfth Topic, Q. 4, #7, 2:191-92.
The direct Turretin quote can be found here.