ERASTUS, or LIEBER, THOMAS, a German physician, who was the formal originator of the opinions now generally denominated Erastian. He was born at Baden in Switzerland in 1523; studied at Basle; and was professor of medicine at Heidelberg. He was afterwards professor of ethics at Basle, where he died in 1584. Erastus was the author of several medical works, but that for which he is chiefly known is the work on Excommunication, in which he promulgated his peculiar opinions; which are known under the name of Erastianism. He taught that the church had no right to refuse participation in the Lord's Supper, baptism, or other ordinances of the gospel, to any one, that it had no right to inflict excommunication or any kind of censure, and that the punishment of all offences, religious as well as civil, should be left in the hands of the civil magistrate.