None of the denominations are political parties, but the Catholic church is immensely political and it's members vote democrat as the leadership agitates for democrat liberal politics.
Other Christian churches fight liberalism.
Other chaurches such as the Presbyterians, congregationalists, and episcopalians? All of the mainstream Protestant Church are liberal theological and support liberal social policies, Even “conservatives bodies such as the Baptists support birth control and easy divorce.
You are confusing Socialism with the Catholic teaching about the common good, charitable justice and our Christian duty to others, especially the poor. To say that the Government has no role in promoting the common good is not Catholic teaching.
The Catholic Church does teach the principle of subsidiarity which is describe as “This tenet holds that nothing should be done by a larger and more complex organization which can be done as well by a smaller and simpler organization. In other words, any activity which can be performed by a more decentralized entity should be. This principle is a bulwark of limited government and personal freedom. It conflicts with the passion for centralization and bureaucracy characteristic of the Welfare State.”
Unfortunately you are correct in that the USCCB does promote a more centralized means of health care reform. I think they are wrong in this. But they are not wrong in teaching that access to health care should be considered essential to the dignity of the human person.