The word “Allah” predates Islam. Each Arab tribe had its own idol gods and goddesses, but a number of tribes also acknowledged the existence of an “unknown god” they called al-ilah, which literally means “the god.” He was considered to be the invisible, supreme deity; however, they did not have a unified concept of who he was. In due time, Allah became “…a universalization of the tribal god who was often referred to as al-ilah (the god). When the tribe encountered another tribe who had a god whom they also referred to as al-ilah, they both thought that they were referring to the same being, and so a universal idea of Allah grew among the Arabs.” (Nazir Ali, p. 26)
Allah and a great number of his 99 other names are commonly used in naming male Arabs today. This tradition was practiced in Arabia even before Islam. Muhammad’s own father bore the name Abd-Allah (slave of Allah)