21 Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.

22 Professing themselves to be wise, they became fools"

When I was growing up my Mother often used  this term, "an educated fool."  As a young girl I was unable to grasp the significance of that phrase, because it just didn't make sense to my very practical and inquiring mind.  After all, to be a fool meant to me that you must be dumb, but in my mind, to be educated meant that you were smart.  These verses of scripture remind me that you can have knowledge, do nothing with it and still miss the boat.   

Paul teaches us here that the creation delivers to every man a clear, unmistakable message about God.   The God who created all that we see around us and constantly sustains it, must be a being of awesome power.  As a result, God holds all men responsible for their refusal to acknowledge what He has shown them of Himself in His creation.  Man's prime directive is to glorify God.  To glorify Him is to honor Him, to acknowledge His attributes and to praise Him for His mighty acts and for His excellent greatness.  Failure to give God the glory that He deserves is man' greatest  insult to his Creator.   

When people rationalize their sin, rather than repent, they prove how completely foolish they are.  Many today develop their own philosophies about God, the universe and even themselves, rather than believe the Word of God.  Man's search for meaning and purpose  without including God will always lead to empty, meaningless and ultimately hopeless conclusions.