Patriotism, love for one’s country, is a moral obligation for citizens. (Love for the other regional communities of which one is a member is analogous to patriotism, and also is an obligation.) But patriotism is love for the true good of one’s country; it is not immoderate nationalism.
Patriotism requires that citizens fulfill a variety of relevant responsibilities. Among these, for Catholics, is defending and spreading the faith in their own nations, as is resisting the dominance of secular humanism, which harms the nation by destroying community.
Citizens are obliged to be dutiful and law-abiding. The moral claims of citizenship should neither be slighted nor overestimated. The common good shapes political society and also limits it; and it is the common good which grounds authority and all the duties of citizens.
As citizens, Catholics should take an active part in public affairs, adhering to the principles of Catholic social teaching. While this political role is primarily the responsibility of the laity, the Church’s teaching specifies a number of purposes they should pursue, including religious liberty, equal justice for all, justice with respect to human life, the protection of marriage and the family, economic justice, and international justice and peace. Citizens also have a duty to vote conscientiously, and sometimes to participate more actively in politics.
All just and applicable laws should be obeyed, but even a just law can be inapplicable in unusual circumstances. One should not comply with an unjust law which is at odds with moral obligation, but otherwise various goods sometimes require complying with unjust laws. However, there is a presumption, not easily rebutted, that laws are just and applicable.
Citizens should cooperate with the criminal justice system, reporting probable crimes, cooperating in official investigations of crimes, giving testimony in court, and serving conscientiously on juries. While supporting the just punishment of criminals, Christians should oppose the use of the death penalty. Citizens ought to pay their taxes. The fact that tax laws are more or less unjust or that some public funds are misused usually does not justify nonpayment.
No war can be just unless several requirements are met, and a development of the Christian tradition in modern times makes it clear that aggressive war is excluded; but a war can be just if all the conditions are met, and citizens should participate in such a war as the law requires. However, participants in a just war should not choose to kill or harm anyone. Moreover, a nation’s deterrent strategy can make its military actions unjustifiable. Christians almost always should refuse to serve in an unjust war.