The proper noun “Allah” solely belongs to The Almighty God, the Truth. Anything succeeding it is regarded as an adjective describing it, while it remains a noun indicative of the True God. It combines all His Attributes, and it needs no introduction from others, whereas the other Attributes attain recognition when added thereto. “Allah” is not given to anyone other than Him, nor should it ever be used for anyone besides Him.
“Allah” is the ever-Existent, the One Who causes existence, Who maintains existence, Who creates everything that exists. Whatever He creates shall perish; He never will: “… say: `Allah!’ then leave them sporting in their vain discourses” (Qur’an, 6:91).
Source : AlIslam