So then this Scripture alone is the fundamental principle by which, and the material from which, every saving truth must be drawn. It is the rule and standard by which every true and also every false teaching about the things of God must be determined (Isa 8:20; Luke 16:29; Acts 17:10, 11). In sum, it is a self-convincing and irrefutable witness and Judge, namely by virtue of its own demonstrated proof by which every controversy which arises over divine matters must be judged (John 5:39, 45).

Synopsis of a Purer Theology, Vol. 1, 23.