Mixing philosophical principles into the articles of faith overturns theology; the Word of God is the common rule of faith

For when theology's own native proofs are confused with heterogeneous and foreign ones — when philosophical principles and the decrees of human reason are dragged beyond their servant role and twisted to prove spiritual theorems and articles of faith — theology is almost wholly overturned, no less deadly to the human race and to the salvation of souls than any plague, however fierce, is to bodily health. If almost the whole swarm (σμῆνος) of the papal party, whom they commonly call scholastics, had not mixed philosophy with Theology, and had not, through ignorance (ἄγνοιαν) of analysis, transferred the principles philosophy claims by right of property to the proving of spiritual things — and if, leaving philosophical matters aside, they had rightly fitted spiritual things to spiritual theorems — there would have been less to this day of execrable errors and of collisions (συρράξεων) ruinous to the church and to be mourned from the deepest vitals; and God's glory and Christ's most precious merit would have been less obscured, as all the orthodox earnestly complain.

But if this first principle is not settled, whatever is done and disputed is in vain, as Nicephorus Gregoras rightly holds (Roman History, book 10, p. 236). For no dispute can go forward unless we first agree with our adversaries in some common principle. And among us and all heretics whatsoever it is agreed that the Word of God is the rule of faith from which dogmas are to be judged — a common principle conceded by all, from which the arguments are drawn, as Bellarmine says in the preface to Disputation 1. In every theological discourse we teach that the first, proper, native, and unmoved principle on which a mind endowed with a sense of piety should rest today, against the papal party and others, is this: Whatever Sacred Scripture teaches is infallibly true.