The question is whether Christians and Muslims worship the same God. Muslims would say that they do. For there is but one God, and to worship anything but that one God is not to worship God at all. Since Christians, Muslims, and Jews all worship the God who created the world, who called Abraham from Haran, and whose Scriptures were completed and perfected by the Qur’an, it seems obvious that they worship the same God.
 But the situation is more complex than that. The word “god” is a generic term. It means whoever or whatever is ultimate or final. But that does not yet identify or specify “god.” “God” can be whoever or whatever an individual or a group regards as ultimate or final. That is behind Martin Luther’s important question in his explanation to the first commandment in the Large Catechism. “What does it mean to have a god?” Luther asks. His answer: “A ‘god’ is the term for that to which we are to look for all good and in which we are to find refuge in all need. … Anything on which your heart relies and depends, I say, that is really your God.” But not everything on which we rely and depend is truly reliable and therefore truly “god.” To spell it with a capital “G” may mean that we would like it to be truly “god,” but it does not yet specify or identify “God.” When Americans sing, “God bless America,” we have a right to ask, “which “god” are you singing about?” It does not change things when Islam adds a definite article, “al” (the), to “Illah” (god) to get the word “Allah,” The God.
 When Islam identifies “Allah,” it does so in two ways. First, Muhammad is the final and perfect prophet of “Allah.” There were other “prophets” familiar to Jews and Christians, including Moses and Jesus. But Muhammad is final because, and this is the second way in which “Allah” is identified, the final will and word of “Allah” was dictated to Muhammad and is absolute in the Qur’an, the book of Islam. Because the Qur’an is final and perfect it is beyond critique.
 Christians identify “god” by the historical event of the crucifixion and resurrection of Jesus, the Jew. Christians are convinced that Jesus of Nazareth is more than a prophet, a precursor of Muhammad. Three things follow from this conviction.
 First, Jesus is the key to the identification of God. The resurrection of Jesus is not the resuscitation of a “righteous sufferer,” a Jewish concept. Rather, Jesus is beyond the power of death altogether. “Death has no dominion over him,” Paul writes in Romans 6:9. That means that Jesus, and not death, has the last word in history, in the cosmos. He is the Messiah of Israel and the world, that is, the final Judge. He will put everyone and everything in its rightful place. In him all things hold together (Colossians 1:17), and through him God will be everything in everyone (I Corinthians 15:28). Because of the resurrection the Trinitarian “Name” of God, Jesus, the Son, his Father, and the Holy Spirit, is now the Name by which God must be identified. The Trinity is the story which must be told of the true and only God because Jesus is the Messiah, because Jesus is Risen.
 Second, in the crucifixion of the Messiah God is revealed to be vulnerable. God is not an imperialistic ruler, but a vulnerable and suffering lover. God does not hand over the created world to its own destructive devices. God is handed over to suffering, pain, and death, the suffering of the Son, his Father, and the Holy Spirit, so that the power of sin and evil and death is overcome by and with good. The dynamic of the Holy Spirit is the dynamic of the Reign of God, God’s “project” of the victory of vulnerable and suffering love over all that is destructive in the universe. There are many individuals and movements, secular and religious, that sometimes or often serve the Reign of God in history. But Jesus alone is the grounding of the Reign of God in the history of God and in the history of the world. When Christians identify God with Jesus of Nazareth, they mean that Jesus is the grounding of all that Christians serve, and anticipate, and hope.
 Third, because Jesus alone reveals and embodies God in history, nothing else does. This introduces into Christianity a call to be humble about all human gifts, structures, and enterprises. The church is the community in which Christians live and serve, but it is not beyond critique and constant reform. It is fallible, sinful, often broken, often betraying its calling. It points beyond itself to the vulnerable and suffering God who lifts it up and makes the community that is “no people” be once again called “My people.” The church listens to and loves its Scripture as the “Word of God,” but it does not worship its book. It knows that it must trust some words of Scripture against other words of Scripture, that it must subject its book to relentless study, analysis, critique, that is must always listen to it anew, learn it anew, translate it anew. For its book is “Word of God” only as it points beyond itself to the Lord who alone is Word and revelation. The principle of self-critique, critique of its traditions, critique even of its book is essential to the identity of the God who is Jesus, his Father, and the Holy Spirit.
 The God of Islam does not seem to be recognizable in these Christian ways of identifying God. But because it is called to be shaped by the cross, Christianity cannot encounter another religion such as Islam on an imperialistic and conquering mission. It is called to witness through its own vulnerable and suffering love. And its judgments are very much penultimate, subject to critique, re-evaluation, and reform.