All truth is God’s truth.

Since God is the Creator of all things all knowledge and truth are sourced in Him.  Thus, all that is true is sourced in God and is, in some way, a revelation of Him.  Our challenge, however, is to pursue truth without the influence of our alienation from God and rebellion against Him.  It is an impossible task.

However, God has revealed Himself to us through His Word and His Son so we can live life wisely and with knowledge of what is true, what is real and what has value.

This is not limited only to the "religious" or "spiritual" spheres, but all truth, in any discipline, is sourced in God. 

The source of this statement is Augustine.  His point was that all of life has coherency.  Our inability to understand, or our ability to distort truth does not negate the reality:  if is true, it is from God.