Source : Webster's Revised Unabridged Dictionary (1913)

Erastian \E*ras"tian\ (?; 106), n. (Eccl. Hist.)
   One of the followers of Thomas Erastus, a German physician
   and theologian of the 16th century. He held that the
   punishment of all offenses should be referred to the civil
   power, and that holy communion was open to all. In the
   present day, an Erastian is one who would see the church
   placed entirely under the control of the State. --Shipley.