It is like this: No person knows the thoughts that another person has. Only that person's spirit that lives inside him knows those thoughts. It is the same with God. No one knows the thoughts of God. Only the Spirit of God knows those thoughts.
We did not receive the spirit of the world. But we received the Spirit that is from God. We received this Spirit so that we can know the things that God has given us.
When we speak these things, we don't use words taught to us by the wisdom that men have. We use words taught to us by the Spirit. We use spiritual words to explain spiritual things.