From the Quran, Chapter 112
Say: He is Allah, the One!
Allah, the eternally Besought of all!
He begetteth not nor was begotten.
And there is none comparable unto Him.
So in short, from the Islamic perspective, God is not a spirit, because a spirit is still a creation, and God is a creator, and not part of the creation, this is a very important concept in Islam and monotheism.
The Originator of the heavens and the earth; He made mates for you from among yourselves, and mates of the cattle too, multiplying you thereby; nothing like a likeness of Him; and He is the Hearing, the Seeing. Quran 42:11
So in short, there is nothing like Allah. Naught is as His likeness in attribute, knowledge, power and providence.
"So Dark the Con of Man"