The Belgic Confession of Faith
Article 2: By what means God is made known unto us
We know Him by two means: First, by the creation, preservation, and government of the universe; which is before our eyes as a most elegant book, wherein all creatures, great and small, are as so many characters leading us to see clearly His invisible attributes, even His eternal power and Godhead, as the Apostle Paul says (Rom. 1:20). All which things are sufficient to convince men and leave them without excuse. Second, He makes Himself more clearly and fully known to us by His holy and divine Word, that is to say, as far as is necessary for us to know in this life, to His glory and our salvation.