# Let no one ... judge you out of your prize

Here Paul refers to false teachers as if they were corrupt judges at an athletic contest who would unjustly disqualify the believers from winning the prizes they deserve, and he speaks of Christ saving a person as if Christ were giving a prize to the winner of such a contest. Alternate translation: "Let no one ... disqualify you from winning a prize" 

# who wants humility

"who wants you to do things to show that you are humble"

# enters into the things he has seen

Here Paul speaks about people who claim to have dreams and visions from God and who talk proudly about them. 

# becomes puffed up for no reason by his fleshly thinking

"puffs himself up for no reason by means of his fleshly thinking" 

# his fleshly thinking

Here the idea of flesh stands for the sinful human nature. "the sinful thoughts he naturally thinks"