Allah is an Arabic word meaning ‘the One God’, the term is commonly used by people when referring to God in Arabic. Many Arab Christians, for example, use the word ‘Allah’. Therefore Allah is God, God is Allah.
In other religions people sometimes use words like Jehova or Yahweh to refer to God. Likewise, some Muslims may prefer to use the term Allah rather than God, even when speaking in English as the term has no plural or gender and its usage connects deeply with the Eastern Islamic traditions. The danger with this is that some people may think that Allah is a different God that Muslims worship, distinct from the God of Christians and Jews.
About a third of the world’s Muslims additionally use an ancient Persian name, Khuda, which also pre-dates the coming of Islam. So historically Muslims have not felt that they were prohibited from using non-Arabic names for God.
Some may argue that in the more subtle meanings, Allah has a distinct advantage over God. Careful study would suggest that this may not be the case, however. A distinguished American scholar, Dr. Umar Abd-Allah (One God, Many Names, Nawawi Foundation, 2004) writes:
“Etymologically, ‘God’ – ‘the one who is invoked in prayer’ – is remarkably close in meaning to the Biblical Elohim and Alaha and the Quranic Allah, which, as we have seen, convey the sense of ‘the one who is worshipped’.”
The Quran itself describes that: “God: there is no god but Him. His are the most beautiful names.”(20:8). As Muslims settle into Western and European cultures, more will find that they are just as comfortable in using European languages to express devotion to God.