egotheism

from The Century Dictionary.

• noun The deification of self; the substitution of self for the Deity; also, the opinion that the individual self is essentially divine.

from the GNU version of the Collaborative International Dictionary of English.

• noun rare The deification of self.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The deification of one's own self.
• noun The view that the idea of God is nothing more than a conception of the self.