Social Doctrine of the Church

There are divergent opinions on the matter:

• "The Church should concern itself with the souls of people! It shouldn't meddle in issues that don't concern it!"
• "The Church should think less about 'incense and prayers' and worry about the poor and other 'concrete matters'!"

Who is right? What is the role of the Church in society?

Providing soup for the homeless? Defending "values"? Fighting for "ideals"? Carrying on "class struggle"? Building "heaven on earth"? (Are we sure?)

Are there "guidelines" with which a Christian can formulate – in conscience – a political choice that aligns with the Gospel and the teachings of the Church?

What do you say? "Social Doctrine of the Church"? Never heard of it...