I have been recently studying through the books of Corinthians. I suppose you could settle on a couple of dominant themes that Paul seems to center on in these two books. In one matter he says much about the carnality that obviously permeates this church. I find it interesting to note also that while they are notoriously carnal they are yet quite focused on ministry. Ministry is then another of the themes that Paul follows.
It seems to me that advocacy of God is one way to characterize Christian ministry. There were those already in Christian circles that had become self-absorbed and misdirected in the matter of Christian ministry. Paul referred to these people as “peddlers”. That is, that they were becoming nothing more than ambitious sales people. It is easy for “evangelism” to become little more than a means to recruit church members and build church growth. Paul is pointing out in these books that true evangelism is the advocacy of God. It is the business of clearly identifying who God truly is and encouraging submission to Him. Paul states that we all are uniquely equipped and gifted for this work and encourages our hearty involvement in it. Paul summarizes this in this portion of Scripture:
2 Corinthians 4:1-7 Therefore seeing we have this ministry, as we have received mercy, we faint not; But have renounced the hidden things of dishonesty, not walking in craftiness, nor handling the word of God deceitfully; but by manifestation of the truth commending ourselves to every man's conscience in the sight of God. But if our gospel be hid, it is hid to them that are lost: In whom the god of this world hath blinded the minds of them which believe not, lest the light of the glorious gospel of Christ, who is the image of God, should shine unto them. For we preach not ourselves, but Christ Jesus the Lord; and ourselves your servants for Jesus' sake. For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ. But we have this treasure in earthen vessels, that the excellency of the power may be of God, and not of us.