autotheism

from The Century Dictionary.

• noun The doctrine of the self-existence of God; specifically, the ascription of self-existence to the second person of the Trinity.
• noun Assumption of divine powers; self-deification; excessive self-esteem. Nineteenth Century.

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

• noun rare The doctrine of God's self-existence.
• noun rare Deification of one's self; self-worship.

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

• noun worship of oneself
• noun belief that one is a deity
• noun belief that one is possessed by a greater power