Paul speaks in this chapter about there being two types of wisdom (worldly wisdom, Godly wisdom) and two types of spirit (the spirit of the world, the Holy Spirit) and there being only one truth.
The natural man cannot make sense of this Godly wisdom born from the Holy Spirit. It is and always will be a great mystery to a fallen world. Prior to receiving Christ, we are on the outside looking in and observing a world that is so far removed from our understanding, it is laughable to even begin to take it seriously.
As a matter of fact this Gospel of grace not only make no sense to the natural man, it makes him angry