At first glance, people could be forgiven for thinking that Islam is basically like Christianity with a few superficial differences. After all, doesn’t Islam teach belief in one God, in revelation, in marriage and family, in charity and justice, in heaven and hell? Let us examine these supposedly shared beliefs. First, it is true that both faiths speak about ‘God,’ but on examination we discover that this word (Allah in Arabic) holds a totally different content for the Christian and the Muslim mind. For the Muslim, God is an unknowable monad who does not reveal himself – he is essentially an eternal will, expressed in an eternal written text sent down in stages (Surah 43:2-4; 56:77-82; 76:23). As Robert Spencer notes, “For Muslims, the Qur’an is a perfect copy of the perfect, eternal book – the Mother of the book (umm al-kitab) – that has existed forever with Allah in paradise.” By contrast, for the Christian, God is a relational being, eternally existing as Father, Son and Holy Spirit, who is revealed clearly and truly in the historical person of Jesus Christ, the incarnate Word of God. The gospels and letters of the New Testament are the historically situated works of eyewitnesses, written under the inspiration of the Holy Spirit, which cohere completely with the inspired revelation of the historical patriarchs and prophets in the Older Testament. The human and historical element is never bypassed in the Christian understanding of God’s self-revelation to man – indeed it is essential to it because God is a covenant-making God.
Second, the nuclear family (Christian marriage) is the fundamental social structure of Western civilization; the unity of marriage between one man and one woman as taught by Christ himself has been foundational to Christian society for centuries. By contrast Islamic marriage is polygamous and is destructive of the unity, harmony and safety of the family. Ordinary Muslim men are permitted up to four wives, plus temporary ‘wives’ whilst on pilgrimage – although Muhammad allowed himself more. Third, both Christians and Muslims speak of charity, but unlike Christian charity directed toward all those in need and a fundamental aspect of Christian missionary history, Islamic charity is solely for the benefit of fellow Muslims, not of the kafir (unbeliever). Fourth, it is true that both Christianity and Islam speak of prayer, but in Islam prayer is a matter of structured recitation five times a day to an unknowable god in the direction of a black meteoric rock in the Middle East (toward Mecca), whereas in Christianity prayer is the interaction of a personal God with man in a covenantal relationship where neither form nor posture is imposed upon it to make it valid.
Fifth, both faiths speak of law and justice. But for Islam there is one law for the Muslim and another for the unbeliever (Surah 3:28; 4:144; 8:12). By way of contrast, in Christian society there is to be love for one’s neighbour and equality for all before the same law rooted in the Ten Commandments (Ex. 12: 49; Lev. 19:34, 24:22; Matt 5:44). This disparity is because Muhammad and Allah hate the kafir (Surah 9:29; 33:60; 83:34; 86:15), whereas the triune God of Scripture loves the world and came to seek and save sinners (Luke 19:10; John 3:16; Rom. 5:6-8). Sixth, in Islam, any hope of paradise is based on the arbitrary will of Allah. Paradise is a libidinous eternal state that may or may not be attained by striving in the cause of Islam, whereas in the Christian faith, salvation is by the grace and love of God alone, by faith in Jesus Christ, who calls us to follow him as his children and love one another (John 13:34-35). Lastly, both religions are missionary faiths that seek to win converts, but in Islam this is by almost any means, including killing, violence and persecution, in order to bring the non-believer to submission (as modelled by Muhammad himself, see Surah 9:29; 61:10). Whereas in the Christian gospel, good news is preached so that people might freely respond to it or reject it (Rom. 10:14ff), and if Christ’s witnesses and ambassadors suffer persecution as a result, they are to love their enemies and do good to those that hate them (Luke 6:27ff).
These stark differences are basic to the persons at the centre of the respective faiths. The true contrast between Islam and Christianity is between the persons of Jesus Christ and Muhammad. Muhammad took up the sword to convert, tax or slay his enemies. Jesus Christ loved his enemies, forgave those who persecuted him and went to the cross because of the great love of God and to win a lost world by making atonement for our sin (1 John 2:2). In short, at almost every point, whilst similar theological terms may be employed by both faiths, their content is radically different. No honest and effective witness can be made to the Muslim without a candid acknowledgement of the radically different starting points we have – of the gulf that exists between the persons of Christ and Muhammad. This fundamental antithesis is expressed in the fact that the Islamic worldview always produces a radically different culture and political system to that of Christianity – grounded in its view of the divine and the foundations of moral order. If we care about Muslims and our society, we will care about facing Islam honestly and clearly in its varied implications.
 A leading Muslim commentator, Beidhawi, suggests that the name Allah is derived from “an [invented] root illaha = to be in perplexity, because the mind is perplexed when it tries to form the idea of the infinite.” See Geisler, Answering Islam, 14.
 Robert Spencer, Did Muhammad Exist? An Inquiry into Islam’s Obscure Origins (Wilmington, DE: ISI Books, 2012), 126.
 For a study of Islamic hostility and violence toward Jews and non-Muslims, see Elias Al-Maqdisi & Sam Solomon, Al-Yahud: The Eternal Islamic Enmity and the Jews (Charlottesville: ANM Publishers, 2010).