To preach Christ is to proclaim the great truths about and the profound implications of His glorious person and finished redemptive work in the place of sinners on the cross of Calvary, making Him known as He set forth the entirety of the Scriptures.
The message declared is God's savings purpose in Christ. Paul and those who genuinely follow him never proclaim a mere system or a set of rules, still less the muddled nonsense being spewed out by heretics. Paul and his fellow laborers do not preach philosophy. They do not preach politics. They do not preach positive thinking. They do not preach themselves. Preaching is not the exercise of the preacher's fancy, the fevered labor of an overwrought imagination...Gospel ministers declare a person, a living person who is the source of all true life, in whom is found the hope of glory, the only fulfillment of the deepest needs of sinful men. That person is Jesus Christ, the incarnate Son of God, the only redeemer of God's elect.
Rob Ventura and Jeremy Walker, A Portrait of Paul: Identifying a True Minister of Christ