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Webster 1913 Edition

Noun.

[Formed like

poetaster

: cf. F.

théologastre

A pretender or quack in theology.

[R.]

Burton.

Noun.

A kind of quack in divinity; as a quack in medicine is called medicaster.

theologaster ‎(plural theologasters)

(rare) A poor theologian; someone who merely pretends to be a theologian.
- 1621, Robert Burton, The Anatomy of Melancholy, II.ii.3:
  But why should the sun and moon be angry, or take exceptions at mathematicians and philosophers, whenas the like measure is offered unto God Himself, by a company of theologasters?