>>2803663You are simplifying Greek and Roman philosophy, In both greek city states and in the roman republic, there was opposition and counter powers to the people in charge, neither the patricians nor the plebian could govern alone and they had to work with each other.
Ceasar got killed for not respecting that, this order only ended with many years of consecutive civil wars, where the idea of a strong man emerged as necessary to keep the peace, even then Augustus never officially abolished the republic.
As for the issue of selfishness, it was generally considered wrong to be selfish, altho you aren't wrong that the core of the argument is different then christianity.
“What brings no benefit to the hive brings none to the bee.” Marcus Aurelius
(Meditations 6.54)
Marcus Aurelius argued against selfishness on the basis of the common good, the idea that a citizen must strive for a larger group. Christianity argued on a individualistic perspective of doing what is right for one's soul. The Main difference between greco-roman and christian is the role of religion, Christians view religion as a deeply personal belief, and while religious communites exist, there aren't the center of religion.
Christians pratice their religion because they believe they'll go to heaven. Pagans view religion as a communal issue and as the continuation of ancient traditions, they practice it to keep communal stability.
However, what christianity brought foward the creation of an institution dedicated specifically to helping the poor, with no real equivalent in the pagan world (except Julian's attempt to create such a system for the pagans)
As for the utopianists, this is also a simplification, while some utopian socialist were christians, plenty also took inspiration by enlightement philosophers (Rousseau) and came to the conclusion of equality between all men by this view rather then religious belief, these utopian socialists condemned Christianity, Gracchus Babeuf is a good exemple.