Gal 6:14, 1 Cor 1:23-24
When Paul failed to preach in Athens, he decided not to preach anything other than that Jesus was the Christ and that Jesus accomplished all the work of Christ on the cross. (1 Cor 2:1-5, Gal 6:14)
1 Cor 2:1 And I, brethren, when I came to you, came not with excellency of speech or of wisdom, declaring unto you the testimony of God. 2 For I determined not to know any thing among you, save Jesus Christ, and him crucified. 3 And I was with you in weakness, and in fear, and in much trembling. 4 And my speech and my preaching was not with enticing words of man's wisdom, but in demonstration of the Spirit and of power: 5 That your faith should not stand in the wisdom of men, but in the power of God.
Gal 6:14 But God forbid that I should glory, save in the cross of our Lord Jesus Christ, by whom the world is crucified unto me, and I unto the world.
It is the power of God and the wisdom of God that Jesus accomplished all the work of Christ on the cross. (1 Cor 1:23-24)
1 Cor 1:23 But we preach Christ crucified, unto the Jews a stumblingblock, and unto the Greeks foolishness; 24 But unto them which are called, both Jews and Greeks, Christ the power of God, and the wisdom of God.