What Spirit do you have and how do you know?  There is only one way to know the thoughts of God, and that is to possess the Spirit of God dwelling within you.  The problem is there were some in the Corinthian church who did not possess the Spirit of God.  They were still the "natural" man who DOES NOT ACCEPT the things of the Spirit of God, for they are foolishness to them and they cannot understand.  You need to listen to "1Cor ch1-2:  Why are there divisions in the church?" to understand who God says there were some in the Corinthian church who rejected the things of the Spirit of God even though they thought they were Christians.Additional points discussed are as follows: There were some who were still carnal, infants in Christ.  "Infants in Christ" are defined in Galatians ch4 and Ephesians ch4 as those who don't have the Spirit of God, still enslaved to the world, are tossed by waves, driven by the wind, and deceived by trickery and deception of false doctrines.Paul could not give them solid food before and even now, still cannot give them solid food because they are still carnal, have jealousy and strife, which is natural and demonic wisdom and not the wisdom from God.This group of prideful/arrogant brethren are instructed they must become foolish to become wise and that their reasonings are useless.Sarcasm is then used to reprimand these prideful people accusing them of many items including possessing wisdom and strength while the apostles are "fools" for Christ, weak and without honor.Reminder the kingdom of God consists of power and Paul will find out if these arrogant/prideful people have any power.