What do we learn from the Qur’an about Christianity in the time of Muhammad?
The Qur'an tells us that Jesus was a prophet of God, like Moses, Muhammad and twenty-two others mentioned by name (Q. 2:136). He was one of those prophets who were sent with a scripture (the Injil) to establish a way of life (shari'a) on earth for a community of people to follow (Q. 5:46). These two high honours confer on him the highest dignity that God can give to any human being. There is no possibility for the Qur'an that he was a false prophet, received a scripture that differed in essence from the message contained in the Qur'an, taught a false doctrine, or led people on any other path than that which is God-given and leads directly to Paradise. As far as Muslims are concerned, any deficiencies, errors or distortions that have crept into Christian practice cannot be attributed to Jesus, but must arise from the subsequent generations of those who were called Christians. This gives us an idea of true Christianity according to the Qur'an and enables us to come to a judgement on those forms of Christianity about which the Qur'an speaks in a critical way.
The Qur'an itself contains only one set of verses that the Muslim scholarly tradition tells us were revealed at the time of a direct encounter between Muhammad and a group of Christians (Q. 3:1-80). These verses are held to have been revealed on the occasion of the visit of a group of Christians from the settlement of Najran, in the south of the Arabian Peninsula, to Muhammad in Madina. The early biography (sira) of Ibn Ishaq records the event and tells us that Muhammad allowed the delegation to pray in his mosque in Madina; in this way he was acknowledging that these Christians were worshipping the one and only God. The verses of the Qur'an cited above indicate a dispute between Muhammad and the Christians from Najran about the true nature of Jesus; the Qur'an corrects excesses to which they have gone in attributing divinity to Jesus and calls them to follow God’s last prophet, Muhammad. The dispute ends in a challenge to mutual cursing (v. 60), from which the Christians ultimately withdraw, according to Ibn Ishaq. This is the occasion for a verse (v. 63) calling the Christians to “worship none but God and ascribe divinity to none other than God”; given the context, this can best be understood as a call to return to the pure doctrine of tauhid taught by Jesus and thus away from the excess of ascribing divinity to Jesus. Mainstream Christian scholars, East and West, would absolutely rebut the suggestion that the doctrine of the incarnation of divinity in Jesus in any way implies that Christians are worshipping something other than or in addition to the one, only and indivisible God. This encapsulates one of the critical perceptions of the Qur'an about Christians in general; here exemplified with reference to the group from Najran meeting Muhammad in Madina.
Two other elements of Christianity are called into question by the Qur'an. There are numerous verses that stress that “God is far exalted above having a son” (e.g., Q. 112:2; 4:171; 2: 116-117). Mainstream Christianity, East and West, does not use the term ‘son of God’ as a biological description but rather as a title for Jesus, describing his unique relationship with God and his task in relation to the creation. It may be that such stress on God not having a son arose from the polytheistic world into which the Qur'an came, but its repeated use as a corrective in a Christian context must surely be taken as a Qur'anic rebuke to any Christians who go to excess in speaking of Jesus in such a way that implies that God was capable of having a male child in a biological sense. Related to this, the other element of Christianity that is called into question by the Qur'an is any suggestion of plurality in God, or more explicitly ‘threeness’ (Q. 5:73, 116; 4:171). Mainstream Christian theologians, East and West, over two thousand years have never spoken of God as “three gods”, but the fact that such a correction of excess is mentioned in the Qur'an must act as a caution to Christians, then as now, that in the formulation of their belief in Trinitarian Monotheism, they must not allow their language to shade over into any imputation of tritheism.
This is as far as we can go on the basis of the Qur'an alone in assessing the state of Christianity in the time of Muhammad. It is always possible, then as now, that there were individuals, and indeed groups, that held doctrines of Jesus or God that would be quite unacceptable to the Christian scholarly community, East and West, but neither Christianity nor Islam should be judged on the excesses of the ignorant or extremists.