The affirmation of moral principles is not within the competence of formal empirical methods. While not denying the validity of such methods, but at the same time not restricting its viewpoint to them, moral theology, faithful to the supernatural sense of the faith, takes into account first and foremost the spiritual dimension of the human heart and its vocation to divine love.
In fact, while the behavioral sciences, like all experimental sciences, develop an empirical and statistical concept of "normality," faith teaches that this normality itself bears the traces of a fall from man's original situation--in other words, it is affected by sin. Only Christian faith points out to man the way to return to "the beginning" (Math: 19:8), a way which is often quite different from that of empirical normality. Hence the behavioral sciences, despite the great value of the information which they provide, cannot be considered decisive indications of moral norms. it is the Gospel which reveals the full truth about man and his moral journey, and thus enlightens and admonishes sinners; it proclaims to them God's mercy, which is constantly at work to preserve them both from despair at their inability fully to know and keep God's law and from the presumption that they can be saved without merit. God also reminds sinners of the joy of forgiveness, which alone grants the strength to see in the moral law a liberating truth....a path of life. Pope John Paul II
