Allah is the Arabic word for "the God" (al-ilāh), the monotheistic Creator of Abrahamic faiths. Muslims see Allah as the one God of Abraham, revealed in the Quran—merciful, all-powerful, without partners or son. Arabic Christians and Jews also use "Allah" for their God.
Muslims claim it's the same God (Quran 29:46). Christians often disagree, citing core differences: Trinity/Jesus' divinity vs. strict unity and Jesus as prophet only. Theological debate on whether conceptions match.