Why does Paul call the Corinthians rich and full?
Paul calls the Corinthians rich and full because of what God had done in their lives, even though they were still carnal Christians. Their riches and fullness came from God's work, not from their own spiritual condition, and Paul desired they reign and experience greater joy.
Les explains that Paul addresses the Corinthians as carnal Christians and yet says they are rich and full because of what God had done in their lives. They had reigned as kings without the apostles, and Paul wished they did reign so that he also might reign with them. Paul was bringing them to a place where they could experience a greater joy of their salvation, and he wanted to be part of that because he was responsible for bringing them out of their paganistic lifestyle. Their richness and fullness were therefore God's doing, even while they still needed to deal with the material things in the cup and restore the Holy Spirit's fullness.