Need for Revelation
For all of the Reformed confessions, then, the sole foundation of all true knowledge of God is God’s own revelation. There can be no true knowledge of God, indeed, no knowledge of God at all, if God does not manifest himself to his creatures. Not only is human knowledge as it now exists clouded and warped by sin, but even the unfallen reason of the first moments of man’s earthly existence could not have been sufficient to reach out to God unaided by God’s own gracious, self-revealing work of mediation.
Richard A. Muller, Post-Reformation Reformed Dogmatics: The Rise and Development of Reformed Orthodoxy; Volume 2: The Cognitive Foundation of Theology, 2nd ed. (Grand Rapids, MI: Baker Academic, 2003), 153.