“The Theodoreans derived their name from Theodorus, known as ‘the atheist’, and adopted his doctrines. Theodorus was a man who utterly rejected the current belief in the gods. And I have come across a book of his entitled Of the Gods which is not contemptible. From that book, they say, Epicurus borrowed most of what he wrote on the subject.”— Diogenes Laertius (c.225), Lives and Opinions of Eminent Philosophers [1]
“Diagoras and Theodorus flatly deny that there were ever gods at all.”— Michel Montaigne (c.1580) [2]
“Theodorus the atheist (fourth/third century BC). Theodorus acquired his nickname because of his professed opposition to the religious beliefs of his time. According to Diogenes Laertius, he studied under Aristippus Metrodidactus (Ѻ) [compare: Aristippus], Misdeeds of Cyrene and Dionysius of Chalcedon, subsequently attracting his own group of followers who became known as the ‘Theodoreans’. He took the view that pleasure and pain were the only important things in life, and that conventional morality should be treated with a degree of flexibility. He regarded himself as a citizen of the world, and lived in a number of different places. This was not always a matter of choice as on more than one occasion he was asked to move on. His flexible approach to morality may have been a contributory factor. He ended his days in Cyrene, even though it had earlier thrown him out. His views on religion may have influenced Epicurus.”— Trevor Curnow (2006), The Philosophers of the Ancient World: an A-Z Guide [1]