Christians define themselves as followers of Jesus Christ. Christians who want to model their lives on that of Christ are commanded to love their neighbor and to work to help their neighbor. Who are our neighbors? Every inhabitant of this planet. Helping this many neighbors seems like an enormous amount of work.
Christians believe Christ suffered and died an ignominious death to atone for the collective sins of humanity. People are far from perfect, and although many do good, and seem to be good, most human actions are principally motivated by self-interest. Governments exist to preserve and protect life and property against the depridations of private interests, but usually fail to protect citizens in a disinterested and evenhanded manner. But even though the rulers of this world may not be fair, Christian scripture promises us that God is fair.
Christianity has its roots in Judaism, and these roots continue to sustain it. Hebraic wisdom has stood the test of time. The first three verses of Psalm 14 record the psalmist's inspired analysis of unregenerate human nature:
The fool says in his heart, “There is no God.” They are corrupt; their acts are vile. There is no one who does good. The LORD looks down from heaven upon the sons of men to see if any understand, if any seek God. All have turned away, they have together become corrupt; there is no one who does good, not even one.