“Of the existence of self, of the world round about us, of logical and moral laws, etc., we are so deeply convinced because of the indelible impressions which all these things make upon our consciousness that we need no arguments or demonstration. Spontaneously, altogether involuntarily: without any constraint or coercion, we accept that existence. Now the same is true in regard to the existence of God. The so-called proofs are by no means the final grounds of our most certain conviction that God exists: This certainty is established only by faith; i.e., by the spontaneous testimony which forces itself upon us from every side.”
Hermann Bavinck, The Doctrine of God, tr. William Hendricksen (Grand Rapids: W. B. Eerdmans Pub. Co., 1951). Quoted by Alvin Plantinga in his paper “The Reformed Objection to Natural Theology” (Proceedings of the American Catholic Philosophical Association,Volume 54).