Roman conservatism - Christianity - Persecution

[Salvianus]

However, it was the denial by Christians to participate in public sacrifice and to acknowledge the semi-divine nature of the emperor which offended Roman ideas of civic solidarity and decency...

As far as I know this was a key point in Diocletian's policy in the later period. I have the idea that the wave of soldier-martyr stories was founded on their disobedience, not their belief per se. I've never really unpacked the famous Nero episode, but which I can see may have been based on the claims of exclusivity or moral condemnation, hence the odd counterclaims of orgies and even cannabalism.

Constantine also retaineed the semi-divine nature of the imperial position by claiming to be "God's vicegerent on earth" and, indeed, the 13th Apostle.

I call Constantine's vision 'Imperial Christianity' as it strongly echoed the traditional world view of an ordered creation with Rome and its Emperor at the top due to divine providence. By Theodosius, adherance to it seems quite similar in import to that for the imperial cult of earlier times.

I find a real sense in Constantine's early words that he was searching to identify his divine sponsor just as Diocletian had promoted the traditional Jupiter and Hercules and only became drawn into 'orthodox' Christianity rather than the cult of Sol Invictus gradually: I don't think monotheism came naturally to him or to many.

The emphasis on urgency in bringing about the Kingdom of God is strong across the New Testament. I'm not sure how much Apocalyptic thinking motivated conversion at this time, but unique or unusual aspects such as living simply, forgiveness of sins, release from worldlyness, openess to women etc may have proven attractive and provided a theistic avenue for current philosphy: certainly by Clement and Augustine of Hippo they were discussing the value and impact of Platonic thought quite consciously.