Allah - the greatest and most inclusive of the names of God. It is an Arabic word of rich and varied meaning, denoting the one who is adored in worship, who creates all that exists, who has priority over all creation, who is lofty and hidden, who confounds all human understanding. It is exactly the same word as, in Hebrew, the Jews use for God (Eloh), the word which Jesus Christ used in Aramaic when he prayed to God. God has an identical name in Judaism, Christianity and Islam; Allah is the same God worshipped by Muslims, Christians and Jews.
"He is God, the One God, Independent and Sought by all; He begets not, nor is He begotton, and there is none like unto Him." (The Holy Qur'an, Surah Al-Ikhlas)

Islam teaches that all faiths have, in essence, one common message: the existence of a Supreme Being, the one and only God, whose sovereignty is to be acknowledged in worship and in the pledge to obey His teaching and commandments, conveyed through His messengers and prophets who were sent at various times and in many places throughout history.