Emperor Constantine I
(306-337)
One of the last strong Roman emperors. He was called Pontifex Maximus, as were all emperors between Caesar Augustus and Gratian.
(Hillsdale - Ancient Christianity)
Support of Christianity
Christianity suddenly advanced under the Christian Emperor Constantine and the Edict of Milan, A.D. 313, allowing the New Testament books to be spread to the East. He assigned Eusebius to prepare 50 copies of the Divine Scriptures, effectively establishing a standard that legitimized all formerly disputed books.
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. The Canon of the New Testament by Milton C. Fisher, Pages 74-75.; Hillsdale - Ancient Christianity)