Witnessing to Muslims is an alien notion to most Western Christians, who shrink from witnessing to even their next door neighbor. But witnessing to Muslims isn't only for frontline missionaries serving in Muslim countries. Witnessing to Muslims is included in Jesus' command for us to "Preach the gospel to every creature." (Mark 16:15)
Because Muslims look different from us, witnessing to them requires us to first confront and overcome our own cultural and ethnic prejudices; inside every Muslim who looks and dresses differently from us is a lost soul that needs to hear the Gospel.
Even people who harm Christians are no worse than Apostle Paul until he was on the road to Damascus, so we should view every Muslim as a potential future Paul to more Muslims.
Second, we need to understand the Muslim prejudices against us. Muslims are taught that it is the Christians who have committed atrocities against Muslims, including during the crusades and the Western colonial rule.
When the opportunity arises, plundering and other atrocities having taken place during the crusades and Western colonial rule should be acknowledged. But it should also be made clear that the perpetrators of those atrocities, while they may have claimed to be Christians, were acting against both the words and the example set by Jesus and therefore were actually not true Christians.
Unlike the crusaders and the colonial powers, Jesus always preached and demonstrated non-violence, even when He was threatened:
"So all those in the synagogue, when they heard these things, were filled with wrath, and rose up and thrust Him out of the city; and they led Him to the brow of the hill on which their city was built, that they might throw Him down over the cliff. Then passing through the midst of them, He went His way." (Luke 4:24-30)
"... Then they came and laid hands on Jesus and took Him. And suddenly, one of those who were with Jesus stretched out his hand and drew his sword, struck the servant of the high priest, and cut off his ear. But Jesus said to him, “Put your sword in its place, for all who take the sword will perish by the sword." (Matthew 26:50-52)
"And one of them struck the servant of the high priest and cut off his right ear. But Jesus answered and said, “Permit even this.” And He touched his ear and healed him." (Luke 22:50-51)