1 Corinthians 1:24

But unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God (KJV)

Then: So why was Paul telling the Corinthians about the power and wisdom of God. They had already been called? They walked through the fire of worry, fear, derision and all other obstacles to belief that are common to men. They knew Christ was their Saviour. They knew God's power of salvation. Just by looking around at their congegation, they recognized the Lord's wisdom as he called believers to his side. The answer lies ahead.

Now: There's no difference in the response of people to the gospel, Christ crucified, as in ages past. People do not change until Christ confronts them.