If we must accept and follow the Church’s moral teaching in any case, why bother trying to understand the point of the moral norms we must follow? Will not such an inquiry merely produce bad reasons for a life which ought to be lived in the light of faith?

The first point to be noted in reply is that the explanation of moral norms to be presented in this book will itself proceed in the light of faith. Clarifications will be drawn from experience and rational reflection, but these will be subordinate to the data of revelation. If the account I propose is in some respects neither required by faith nor intelligible in itself, then to that extent it ought to be ignored. But if it helps to clarify what we believe, then it can be enriching and useful.

It will be enriching because human action is not simply outward behavior and moral norms are not simply devices for eliciting behavior. Human action fulfills human persons; by it they share in community. Human moral norms make possible truly good human acts and shape them toward human fulfillment. Christian action is destined to last forever in Christ. Christian moral norms make possible our fully conscious and free sharing in the life of Jesus and cooperation in his redemptive work; Christian lives of holiness in this world contribute to the joy of eternal life.

At the Last Supper, our Lord Jesus told the apostles he regarded them, not as slaves, for a slave “does not know what his master is doing; but I have called you friends, for all that I have heard from my Father I have made known to you” (Jn 15.15). An important and wonderful part of God’s gift to us in making us sharers in his own life is his showing us the point of the moral norms we must follow, as we live our human lives by following the way which Jesus is. By knowing what God is doing, we understand what we are trying to do; our action has greater inherent richness and has even now the fruit of joy in divine friendship.

Moreover, this same action becomes by deeper insight a better and more perfect gift to God. The more we put ourselves into what we do, the more our lives constitute that rational worship to which St. Paul teaches every Christian is called (see Rom 12.1–2). God wants from us not empty acts of ritual but our very lives (see Is 1.10–20; 29.13; Hos 6.6; Mi 6.6–8; Mt 9.13; 12.7; 15.8–9; Heb 10.5–9; 13.16). Enriched with God’s own love and united with the life of Jesus, our lives become a holy and acceptable sacrifice.

By the grace of God we are what we are, and his grace is not fruitless. By it we share the dignity of active and contributing members of the divine family. Being familiar with God, we must be conscious of what he is about and must consider what we are about. In this way, we will grow to maturity as children of God and please our heavenly Father by the richness of our accomplishments (see Mt 25.14–30; Lk 19.11–27; Jn 15.1–8). Thus we may hope to share in the accolade of the heavenly Father: “You are my beloved Son; with you I am well pleased” (Mk 1.11).

In sum, human acts express rational choices. The better one understands what one is doing, the richer in significance one’s acts are. The richer in meaning a good act is—other things being equal—the better it is. Goods can be realized in acts, and so can contribute to completion in Christ of themselves, only if they are in some way known by the person acting. Thus lack of understanding when understanding is possible detracts from the gift one could and should be offering to God.

There also are several secondary ways in which an understanding of the general norms of Christian life will be helpful. Study of this work will help answer a question much discussed today: What precisely does Christian moral teaching add to the body of moral truth which could be known by upright persons even without the light of faith? Moreover, the explanations to follow will provide the principles by which the Church in her teaching can explain and defend specific norms of Christian morality when these are misunderstood and called into question. Finally, to a considerable extent, priests in their preaching ought to stress the normative principles of Christian morality. The perceptive student will find the present treatise very helpful in this work.