Allah الله (pronounced: Allaah), is traditionally used by Muslims as the Arabic name of God. The word Allah is not specific to Islam; Arab Christians and Jews, and the Catholic Maltese, also use it to refer to the monotheist deity; for example in Arabic translations of the Bible.
Although the name "Allah" is most commonly associated with Islam, it was also used in pre-Islamic times.
It was used by Arab Christians in the pre-Islamic Umm al-Jimal inscription (6th century).
http://en.wikipedia.org/wiki/Allah
The third is an undated but probably 5th century inscription found in a church at
Umm al-Jimal in northern Jordan, a monument to one Ulayh ibn Ubaydah, the secretary of a Roman cohort. This, incidentally, refers to God with the word Allah, showing that Arab Christians' use of the word predates Islam.
http://en.wikipedia.org/wiki/Pre-Islami ... scriptions