Imagine you are entering a dark room.  You can see the vague outline of furniture; a table here and a lamp there.  It could be the most beautiful room full of Victorian furniture, impeccably decorated walls, and priceless artwork, but without the lights on, you can only see odd shapes and outlines.  You cannot truly enjoy or appreciate the beauty without light to illuminate it for you!  God’s truth is like that room.  Mankind knows it’s there, but understanding it and applying it requires the light to be turned on.

1 Corinthians 2:10-13 – But God has revealed them to us through His Spirit. For the Spirit searches all things, yes, the deep things of God. For what man knows the things of a man except the spirit of the man which is in him? Even so no one knows the things of God except the Spirit of God. Now we have received, not the spirit of the world, but the Spirit who is from God, that we might know the things that have been freely given to us by God. These things we also speak, not in words which man’s wisdom teaches but which the Holy Spirit teaches, comparing spiritual things with spiritual.