Well, given that not long after the emperor converts it became deadly to possess the version of Jesus's sayings which claims he said "Let one who has become wealthy reign, and let one who has power renounce <it>" (allegedly said at the time when Tiberius was the first emperor to inherit the kingdom due to dynastic claim vs accomplishments and had abandoned ruling to party but wouldn't turn over the position to anyone else) - probably just a wee bit of mind changing.
Roman emperor was the head of the church, so Christianity became a political tool to manage the population.
The Empire was politically managed by having it divided into two halves, a Greek speaking eastern half and a Latin speaking western half. Which ended up shearing Christianity into Catholic and Orthodox.