Democracy and virtue go hand in hand. Freedom cannot exist without a corresponding level of responsibility. Democacy, likewise, needs a virtuous electorate to work smoothly. I am not advocating a utopian society based on an unattainable level of perfection, but one based on individuals who try to make the best of the gifts God has given them.
I believe that socialism (and other enlightenment utopian "isms" that rely on collective human means for some end of "salvation") stands in contradiction to this. In essence, while masquerading as the ultimate form of charity, socialism presents a twofold danger.
First, contrary to its claims, it is inherently rooted in the sin of envy. The Decalogue of Exodus (10 Commandments) specifically states "Thou Shalt not covet" but I think that is exacty what the class warfare involved with socialism does.
Secondly, socialism inhibits the virtues of courage and fortitude because it creates an entitlement mentality (again, masquerading as charity) that lets the government do everything, taking away an individual's personal responsibility to his neighbor, which also stands in contrast to the principle of subsidiarity, which states that men ought to govern themselves at the most local level whenever possible.