From First Corinthians by George T. Montague, SM, commenting on I Corinthians 2:1-5
The same divine paradox, shown in the content of the preaching (1:18–25) and in the social position of the hearers (1:26–31), applies equally well to the preacher from whom they first heard the good news. This good news did not demand but rather forbade pretentious speech and this-worldly wisdom, because the gospel has no need of it, any more than a golden statue would need to be decorated with crepe paper. As the mystery of God (2:1), it bears its own power.
In our language “mystery” often means something unsolved. In Paul’s day the Greek word was often used in referring to the “mystery religions,” which kept their rituals secret, and thus it bore the notion of secrecy. For Paul, the gospel is the secret of God’s heart, but it is a secret now revealed and proclaimed by the Apostle.
In saying I resolved, it appears that Paul made a conscious decision to avoid the “continuity” method of introducing the gospel and went unabashedly for “discontinuity”—an emphasis on how the cross is different from mere human expectations, reasoning, and posturing. Paul has called the cross a stumbling block, or scandal (1:23). That scandal was Jesus Christ, and him crucified.
While this repeats the content of the message already discussed above, the emphasis here is on Paul’s decision to know nothing else among them. The Corinthians did not need more rhetorical bells and whistles, and Paul would not entertain them with such. He will later speak about knowing the risen Christ (15:8) and the power of his resurrection (Phil 3:10). But the Risen One is also the Crucified One.