Complex sentence: Casaubon was appalled by the treatment of Barnet and considered it a "violation of Christian ethics"; he later said that he did not think that changing one's mind on such a matter of religion was a criminal matter.
Split into simpler sentences: Casaubon was appalled by the treatment of Barnet and considered it a "violation of Christian ethics". He later said that he did not think that changing one's mind on such a matter of religion was a criminal matter.