In the third-century pagan world, hate and envy prevailed. The propertied classes were hated by the poor, the working classes hated the middle class, while the army was hated by all classes. Christianity preached love to neighbours, philanthropy towards strangers, as the Emperor Julian, though hostile, reluctantly admitted. It would bring these mutually antagonistic classes together, as the Emperor Constantine saw. Pagan religions and philosophies revealed this, too, but failed to practise it, had become cold. This is one of the reasons, apart from the alleged visionary experience of a cross in the sky, which persuaded Constantine to adopt Christianity as the official religion of the Roman Empire.
-- Notebooks Category 17: The Religious Urge > Chapter 5: Comments On Specific Religions > # 31