Koran, 4:156-159 "That they rejected Faith; That they uttered against Mary a grave false charge; That they said (in boast): We killed Christ Jesus the son of Mary, The Messenger of Allah. But they killed him not, nor crucified him, but so it was made to appear to them, and those who differ therein are full of doubts, with no (certain) knowledge, but only conjunction to follow, for of a surety they killed him not. ... And on the Day of Judgment He (Jesus) will be a witness against them (Christians)."
St. Paul, 1 Corinthians, Chapter 1, Verses 23, 24: "But we preach Christ crucified: unto the Jews indeed a stumblingblock, and unto the Gentiles foolishness. But unto them that are called, both Jews and Greeks, Christ, the power of God and the wisdom of God."
St. Paul, 1 Corinthians, Chapter 2, Verse 2: "For I judged not myself to know anything among you, but Jesus Christ: and Him crucified."