God’s thoughts are not our thoughts, and the God-centered approach which the Bible makes to problems of life and thought is, in the highest degree, unnatural to the minds of sinful and self-centered men. It calls for a veritable Copernican revolution in our habits of thought, and is slowly and painfully learned. On the other hand, it is entirely natural for sinners to think of themselves as wise, not by reason of divine teaching, but through the independent exercise of their own judgment, and to try to justify their fancied wisdom by adjusting what the Bible teaches to what they have already imbibed from other sources (“modern knowledge”). Professed re-statements of the faith in modern terms often prove to be revisions of the faith to make it square with popular intellectual fashions. This process of assimilating God’s revealed truth to the current religious and philosophical opinions of men is the essence of the speculative method in theology which Scripture repudiates. Yet, we all do it constantly, more or less, for sin is present with all of us. As usual with sinful lapses of mind, we are largely unconscious of our lapses and only become aware of them as we test ourselves by Scripture and ask God to search our minds and teach us to criticize our own thinking. This, once again, is a discipline that none may shirk.
From: “Fundamentalism” and the Word of God: Some Evangelical Principles by J. I. Packer (Leicester: The Inter-Varsity Fellowship, 1958), p. 70.