IMO, Rome saw an advantage in adhering to a -version- of the religion ... and in overcoming what it termed the 'pagan empire' (Greek in part). At Nicaea in 325,

IMO, Rome saw an advantage in adhering to a -version- of the religion ... and in overcoming what it termed the 'pagan empire' (Greek in part). At Nicaea in 325, the religion was overhauled. Stamping out the Eleusinian mysteries was part of that process. In the 380s, Theodosius helped that along by beginning the destruction of sites and the persecutions (tactics far from Christ-like), as did Theophilus, then Cyril. All designed to consolidate the takeover.