The Collaborative International Dictionary of English v.0.48:
Ungod \Un*god"\, v. t. [1st pref. un- + god.] 1. To deprive of divinity; to undeify. [R.] --Donne. [1913 Webster] 2. To cause to recognize no god; to deprive of a god; to make atheistical. [R.] --Dryden. [1913 Webster]