The Corinthians cost Paul hardship, a ministry opportunity, and sleepless nights. He was in conflict and turmoil over their sins and situation. Where is the joy in all of this?

As Christians who look back into the OT, all of the mysteries are revealed to us. Christ is the answer. The OT is about Christ. Don't look at the OT as the means to earn your righteousness. Look at it as the means to deepen your love and obedience to Christ.