Why was Paul so upset with the Corinthians in first and second Corinthians?
Paul was upset because the Corinthian believers, though genuinely saved and placed into the Body of Christ, remained spiritually weak and carnal, still controlled by the Old Adam rather than the Holy Spirit. They were like babes needing milk, not growing in the Word as God expects.
Les explains that the word "carnal" here describes believers who have not really come out of the fleshly experience and are still under the control of the Old Adam rather than the Holy Spirit. Unlike Romans chapter 8, where "carnal" applies to the unsaved individual, these Corinthians were saved, in Christ, but so weak spiritually that Paul called them babes. He fed them with milk, not solid food, just as a newborn cannot take solid food. Les says he has patience with new believers and does not expect them to suddenly comprehend all the deep things of God's Word, but he looks for growth. He tells his classes that if they are not more steeped in the Word now than a year ago, then he has failed and they have failed, because God expects growth from His children. The Corinthians, however, were still so steeped in the flesh that it got Paul all uptight in this first and second letter. They were believers, born again and placed into the Body of Christ, yet still so fleshly minded.