“The Missionary among Muslims (to whom the Cross of Christ is a stumbling block and the atonement foolishness) is driven daily to deeper meditation on this mystery of redemption to a stronger conviction that here is the very heart of our message and our mission.” –Samuel Zwemer
“Wherever there is the obscuring of the beauty of the Cross, it must be unveiled.” –Kenneth Cragg
These are quoted in the conclusion of Cross and Crescent: Responding to the Challenge of Islam by Colin Chapman. In closing Chapman says:
Walking the way of the cross in witnessing will mean testifying as best as we can it is “in the face of Christ” that we see “the light of the knowledge of the glory of God” (2 Corinthians 4:6). However weak our efforts to bear witness to Christ crucified as the very heart of our message, we shall find that for those whom God has called – of whatever community and whatever faith – Christ on the cross will be recognized as the supreme revelation of “the power of God and the wisdom of God” (1 Corinthians 1:23-24).
Related: When should we focus on the cross? (and especially the comments)