He conducted religious reforms

One of the most interesting facts about Claudius is that he conducted religious reforms. Claudius, as the author of a treatise on Augustus' religious reforms, felt in an excellent position to institute some of his own. He was concerned about the correct shape of a state religion. He rebuffed the Alexandrian Greeks' proposal to dedicate a temple to his divinity, claiming that only gods may choose new gods. He restored lost festival days and eliminated many unnecessary ceremonies created by Caligula. He reinstated traditional customs and archaic language.

Claudius was concerned about the proliferation of eastern mysteries within the city and sought more Roman substitutes. He emphasized the Eleusinian Mysteries, which were popular throughout the Republic. The Eleusinian Mysteries were annual initiations for the Demeter and Persephone cult headquartered at the Panhellenic Sanctuary of Eleusis in ancient Greece. They are the most famous of ancient Greece's hidden religious practices. He banished foreign astrologers while rehabilitating the ancient Roman soothsayers (known as haruspices) as a replacement. He was particularly critical of Druidism for its incompatibility with the Roman state religion and its preaching operations. Claudius prohibited proselytizing in any religion, even in areas where indigenous were free to worship. It is also said that he once evicted the Jews from Rome.