“Allah” is the Arabic word for “God” and has been so long before the existence of Islam. The names “Allah” and “God” are generally interchangeable within the Muslim religion and in Middle Eastern cultures. Some English translations of the Qu’ran (Koran) use the name “God,” others use “Allah.”
This sometimes comes as a surprise to Christians who were raised in Western cultures. Among former Muslims, many converts to Christianity commonly refer to God as “Allah.” (This is despite the fact that they recognize clear differences in the character of God as described by the Bible compared to Islamic writings. For example, although both Christians, Muslims and Jews firmly believe there is only one God, Christians have the additional doctrine of the Trinity.) Of course, the word “God” does not actually appear in the original Hebrew or Greek manuscripts of the Bible, accepted as Holy by both Christians and Muslims. “God” is an old English word which developed from an Indo-European word, meaning “that which is invoked,” which is also the ancestor of the German word Gott (meaning: God)
The Navigators, a well-known evangelical Christian organization, published the following: “…It’s interesting to observe that, in rejecting the Athenian’s erroneous concept of God, Paul did not reject the word they used for God, Theos, which was the common Greek word for God. Some Christians unthinkingly say ‘Allah is not God.’ This is the ultimate blasphemy to Muslims, and furthermore, it is difficult to understand. Allah is the primary Arabic word for God. It means ‘The God.’ There are some minor exceptions. For example, the Bible in some Muslim lands uses a word for God other than Allah (Farsi and Urdu are examples).
But for more than five hundred years before Muhammad, the vast majority of Jews and Christians in Arabia called God by the name Allah. How, then, can we say that Allah is an invalid name for God? If it is, to whom have these Jews and Christians been praying? And what about the 10 to 12 million Arab Christians today? They have been calling God ‘Allah’ in their Bibles, hymns, poems, writings, and worship for over nineteen centuries. What an insult to them when we tell them not to use this word ‘Allah’! Instead of bridging the distance between Muslims and Christians, we widen the gulf of separation between them and us when we promote such a doctrine. Those who still insist that it is blasphemy to refer to God as Allah should also consider that Muhammad’s father was named Abd Allah, ‘God’s servant,’ many years before his son was born or Islam was founded!”