That Jesus was crucified is a brute fact of history acknowledged by non-biblical sources (Tacitus, Mara Bar Sarapion, Lucian, etc.), as well as the writers of Scripture. But we recognize that history is only in a small sense about dates, names, and places. These things are better thought of as the starting point for its larger concern, which has to do with correctly interpreting an event in all of its fullness and depth so it might be placed in its proper context. It’s one thing to know that Christopher Columbus left Spain for the new world in 1492. It’s quite another to understand how that shaped humanity’s story, but that’s just what the discipline of history seeks to do.
When Paul brings up “the message of the cross,” (1 Corinthians 1:18), his purpose is to expound upon the meaning of the crucifixion relative to the divisive conditions at Corinth. The disciples there had elevated certain leaders (their teachers), to celebrity status and were arguing over which person (and which style), belonged at the top. To be fair about it, they were only importing their cultural values into the church as arguments over schools of philosophy, rhetoric, and what constituted true wisdom were ongoing debates in Greek society. (You can get a taste of all of this in Acts 17:16ff). Choosing up sides in this manner was natural in Corinth. In fact, it was a way of life. But it was killing the church.
Apparently, the conflict centered upon Paul and Apollos (3:4-6, 4:6), and the differing styles they employed in sharing the good news. Apollos was from Alexandria and “eloquent” (Acts 18:24/NAS,ESV). This is probably Luke’s way of indicating he had been schooled in rhetoric there (the NIV translates the same word as “learned”). Contrast this with Paul’s admission concerning his lack of speaking ability (2:1-5; 2 11:6), and the agreement of some at Corinth with his assessment (2 10:10). His giftedness seems to have been more along the lines of knowledge and writing (Acts 22:3,26:24; 2 Corinthians 10:10). Apollos and Paul—two different people with different gifts preaching one Lord. How tragic that the Corinthians missed the message and chose to exalt the messengers! How sad this still happens today.
Paul’s point about speaking well (with wisdom & eloquence—v. 17), must be contexualized in the same manner as his statement about not being sent to baptize. He isn’t against people who speak well or with wisdom any more than he is against baptism (remember he reasoned and persuaded people—Acts 18:4). What he’s against is style being primary and Christ being secondary. He is against anything that exalts and points to the messenger rather than the message of Christ crucified. And, the situation at Corinth had sadly deteriorated to just that point.