His system, he might claim, only seems unattractive to us because we have totally lost the community spirit that makes people want to be together. Citizens in his ideal republic are not forced into a community: they agree to it for their mutual benefit. He might argue that the citizens of ancient Greece and Rome were very active and capable of achievements that we have not come close to emulating since. The community spirit that united them did not intrude upon their individuality; rather, it gave individuality an outlet for its fullest expression.
Pathos, the emotional or psychological dimension, also plays a role. Beliefs are formed not only by rationalisation but also by "attraction". Arguments we "like", whether because they are presented beautifully or because they resonate with our hopes, will usually be more persuasive than ones we find unpleasant. I think this partly explains why, despite having some great minds in the cause, atheism continues to be an important minority viewpoint. Whatever its intellectual credentials, taken seriously it offers a very bleak outlook.