The social dispute over justice that is in a great crisis, must not be limited to social and economical criteria only. This is proved by the elementary experience, since attempts to overcome injustice only on this level are not effective. The anthropological and personalist criterion is necessary here. Only this criterion allows one to integrally define a man – also in his relations with others – as a person. Also justice has a personalist character, and because of this it is not a value that is only added to a man. As such, it is also an objective value that has an obligatory character, which is difficult to justify, and the more so to make it come true, without the Christian Revelation. The event of Jesus Christ, with the preparation given in the Old Testament, shows man’s sin as the fundamental source of injustice. This is why in an encounter with injustice only God’s mercy is effective, as the only factor – through Jesus’ paschal mystery – that overcomes sin. It is not tantamount to giving up justice, but to practicing it – as in Jesus’ understanding surrendering to the criteria of justice is a necessary condition of mercy, so that the sin can be judged and overcome, and the man can be saved.