One of the chief obstacles to a Muslim becoming a Christian is the doctrine of the Trinity. Muslims believe there is only one God—Allah—and that Christians practice polytheism (the worship of many gods). In his book The Faith, Chuck Colson argues nonetheless that we shouldn't shy away from teaching the Trinity. In fact, he's found that the very doctrine itself is one of the best evangelistic tools at our disposal. He writes:

Take the case of "Farid," originally a nominal Muslim who came to the United States in 1993 to study. He fell under the spell of the MSA [Muslim Student Association] and soon joined their ranks, evangelizing. In debates with Christians, he contended that the Trinity was idolatry, or, as the Muslims call it, "shirk." But in those same debates, he found his own positions weak when he was forced to argue that Jesus didn't die on the cross, only appeared to, as Muslims believe. Although he was warned against investigating the topic, Farid began to study…

Farid soon gave up his evangelizing on behalf of the MSA, continuing his search more deeply into Christian theology. He came to see that far from rejecting the Trinity, it "was the only logical explanation of what is reported in the New Testament, and [it] was logical and non-contradictory, just as a wave-particle duality principle in physics was the only plausible yet unbelievable and seemingly contradictory way to explain the world."

Eventually, Farid's search brought him to the point of exhaustion, where, in his imagination, he lay outside the gates of the City of God. At this point he cried out to God to rescue him, if God would. "I felt a strange feeling of God's love, as if he was telling me that I am his, and that he will love me and take care of me for the rest of my life and after." This experience led to Farid committing himself to a new life as a Christian… God became Farid's eternal Father, "an infinite being who cares about me personally, and who wants me to be fully committed to him."