Who Defines Sin?

It seems that as political correctness strives to elevate its values to
that of moral imperatives, it is defining sin as that which contradicts
its own political priorities. See for, example, the article by Chris
Satullo of the Philadelphia Inquirer on July 1, 2008, "A Not So Glorious
Fourth" where he calls a "national sin" the alleged torture of political
prisoners.

This is what happens when one excludes God from public debate. To fill the vacuum (although it's not really a vacuum) you substitute your own personal politics for God's laws.

However, every one of us to some extent, has this tendency to define what is sinful based on our own personal standards. This is exacerbated by the common but erroneous belief that there are no absolute values, that morality is personal and private. But there are absolutes. As Creator of the universe, God has the right to express His sovereignty and rule over all. He does this through natural laws and through moral laws, written in the consciences of men and women, and also objectively written in His divine revelation in Scriptures.

There is indeed a great reason to pray,

Thy kingdom come, Thy will be done on earth, as it is in heaven.