Divisions in the Church
The church in Corinth was dealing with major issues. A man was sleeping with his stepmother; others were participating in idol worship, including sleeping with the temple prostitutes; some were hungry while others had abundance and were not sharing. The list could go on about the dysfunction in Corinth.
Before Paul addressed any of these issues, he addressed the issue of unity. The church in Corinth was becoming divided, schisms were forming over who was the best preacher/leader of the church. Paul had started the church and Apollos took over for him. At some point, Peter either joined those in Corinth or his reputation was so great that it created a following. Regardless of the details, those in Corinth were splintering over which leader the people followed.
Paul was appalled and in a sarcastic tone asked those in Corinth if he was sacrificed for them. Obviously, the answer is no, Paul was not crucified for them, Jesus was. It is only in understanding the crucifixion and the resurrection can we be unified. It is through Jesus's selfless act of becoming a man, living a human life, dying a criminal's death, and rising from the dead that we can be unified. The power to put aside your own desires and to submit your self to the greater body is done only because of Jesus. You do not have the ability in your self, you do not have the power to lay aside your selfishness apart from the cross of Christ. Do not strive in your own ability to be unified. Focus on Jesus and the Cross and He will enable you to be unified.