The Muslim Shahada (creed or statement of witness) is very simple: There is no god but God, and Muhammad is the apostle of God.
Muhammad’s fundamental mission was to combat idolatry and bring mankind back to the worship of the one true God. He saw himself as the last of a long line of prophets stretching back to Adam, with the key figures being Noah, Abraham, Moses and Jesus. He believed that all the prophets had brought basically the same message: to believe in the one true God and to follow certain moral rules and ritual practices. The ritual (and even the moral) elements might change slightly due to different times and cultures, but the key core belief must remain the same.
Muhammad did not only believe that there could only be one God but also that God himself was absolutely one, separate and unique. Nothing could be associated with him, no idol or secondary god. Although Muhammad had in mind primarily the idols that were worshipped in Arabia at that time, this conviction had serious implications for the Christian doctrines of the divinity of Jesus and the Trinity. Muhammad did not fully understand these, but to the extent that he did understand them, he definitely rejected them.
Another consequence of this view of God is the belief that he is totally ‘other’. As Islam’s doctrines developed, the religious teachers asserted that no human language could describe him. To say, for example, that he is a God of love would make no sense, because God’s love is not like human love. God cannot be limited in any way. He is all-powerful and unknowable. Man is his slave and cannot hope to have a personal relationship with him.
In the face of this doctrine that seems to isolate man from God completely, how can the Christian respond? Even though both Christ’s deity and his crucifixion are strongly denied in the Qur’an, he is an important figure, and Muslims are attracted by the person of Christ. One possible bridge lies in the expression the Word of God. In the Qur’an, Christ is described as ‘Christ Jesus the son of Mary, an apostle of God and His Word, which He cast into Mary and a Spirit from Him’ (Sura 4:171). Although this passage in its surrounding context, like many others, asserts strongly that Jesus was only a man and goes on to deny the Trinity, the Word of God as a title for Jesus is very familiar to Muslims.
Muslim scholars say that all that it means is that God spoke and Jesus was created in the womb of Mary. But, if the person is open, we can take them to John chapter 1 and show them that the Word of God is eternal, existed before all things and was deeply involved with the creation. It is this Word that became a man. Jesus, therefore, is not simply a prophet, which is all Muhammad ever claimed to be, but someone much greater.