For indeed Jews ask for signs and Greeks search for wisdom; but we preach Christ crucified, to Jews a stumbling block and to Gentiles foolishness, but to those who are the called, both Jews and Greeks, Christ the power of God and the wisdom of God. Because the foolishness of God is wiser than men, and the weakness of God is stronger than men. 1 Corinthians 1:22-25
So very often we are amazed that the gospel is rejected by the world. Yet what God has revealed is perfectly antithetical to what the world desires. For some it is a great sign here and now, for others it is the demand that their intellectual pride be catered to in one regard or another. Paul surely could have talked to them about the verifiable miracles of Christ. Being an apostle he could have shown them a miracle; as Paul himself was used by God to do many miracles. Being a man of great education and learning he could have engaged in an intellectual debate that would tickle their fancy. However, Paul did not fall into either pitfall. Far from this: "I determined to know nothing among you except Jesus Christ, and Him crucified." When Paul spoke to the learned he talked about Jesus Christ, and he resolved not to be ashamed of the gospel. It is a great example for every believer to follow.