A government decides to invade the territory of a neighboring country. He wants more power, more wealth, more slaves, more fame. 

The decision of that government, and so many other similar decisions, is simply bad. 

arises here the questions: Why do we say that something is wrong? Where does our conviction come from in the face of so many acts committed by ourselves or by others?

The answers are not easy, because we do not always have the same parameter to say what is good and what is bad, and because there are many theories in turn on the subject. 

A theory that reduces good and evil to subjective sentiments or cultural perspectives will say that we use those terms in a variable way and without reaching valid truths for all.

For those who are facts the result of blind forces, fixed mechanisms, uncontrollable natural processes, war (and so many other human actions, also good calls) should not be judged as bad or good. 

Despite the different theories and ways of seeing things, at the bottom of the human heart there is a criterion that tells us that certain facts should not happen, and that bad actions deserve to be corrected and punished.

This criterion implies, implicitly or explicitly, that we have a free will, that we are open to different options, and that among those options some are good and others are bad. 

That is why, when we firmly condemn the aggression of an army over a defenseless people, we do so from the conviction that not everything is lawful, and that the bad is to be neutralized in the best possible way.

History and experience remind us that not always evil is stopped or the culprits are punished. But reason and faith lead us to recognize that what is not corrected in this life will be in the future life.

Therefore, evil can never be the ultimate or definitive. A healthy love for good and justice pushes us to stop injustice, to promote good deeds, and to wait in God to give each one according to his works (cf. Rm 2, 5-8; Ap 20.13).