structural:expansion
Ancient Roman policy

The Romans tolerated most religions, including Judaism, and encouraged local subjects to continue worshipping their own gods. They did not however, tolerate Christianity, because of the Christian refusal to offer honours to the official cult of the emperor, until it was legalised by the Roman emperor Galerius in 311. Holmes and Bickers note that as long as Christianity was treated as a part of Judaism, which was generally tolerated because of its antiquity and its practice of making offers on behalf of the emperor, it enjoyed the same freedom, but the Christian claim to religious exclusivity meant its followers found themselves subject to hostility.

The early Christian apologist Tertullian was the first-known writer to employ the term "freedom of religion" (libertas religionis). The Edict of Milan guaranteed freedom of religion in the Roman Empire until the Edict of Thessalonica in 380, which outlawed all religions except Christianity.