The Islamic creed is that THERE IS NO GOD SAVE ALLAH AND THAT MUHAMMAD IS HIS PROPHET. (LA ILAAHA ILLA-ALLAH MUHAMMADUR- RASOOLILLAH).
Muslims believe that Allah is ONE. He was neither begotten nor does He beget. He has no Partner. He is the Beginning and He is the End. He is Omniscient and Omnipresent.
The Quraan says that He is closer to man than his jugular vein yet He cannot be encompassed by human intellect.
See the following verses of the Quraan:
Imam Ali says in a supplication:
"Oh God, verily I ask Thee by Thy Name, in the name of Allah, the All-merciful, the All-compassionate, O the Possessor of Majesty and Splendour, the Living, the Self-subsistent, the Eternal, there is no God other than Thou, Oh He of Whom no one knows what He is, or how He is, or Where He is, or in respect of what He is, And yet, we know that He is."