''When Christ calls a man, he bids him come and die," writes Dietrich Bonhoeffer in his spiritual masterwork, "The Cost of Discipleship." And Bonhoeffer did die. For him, the cost of opposing the Nazis, in obedience to Christ, was to be executed vindictively, just two weeks before the Flossenburg concentration camp, where he was imprisoned, was liberated by the U.S. military. This weekend is the anniversary of his death, April 9, 1945.

Easter Sunday had fallen on April 1. Back then, there was no "Divine Mercy Sunday." But today, looking back, we can count Bonhoeffer's death as if close to that celebration. In fact, he was condemned to death on April 8.

The timing is appropriate to Bonhoeffer's spiritual insights, because of his famous criticism of what he called "cheap grace" (German, "billige Gnade"). One might just as well translate it as "cheap mercy."

Bonhoeffer was a Lutheran pastor, yet what he says about "cheap grace" applies to us strongly, in part because Catholic sensibility in America and Europe has been strongly influenced by Protestantism -- not so much by the direct influence of a vibrant Lutheranism, but rather by an indirect and vague influence of a secularized ethic, which finds it "nice" to declare everyone as already saved, no matter what they do.

A central passage captures the essence of his thought: "Cheap grace is not the kind of forgiveness of sin which frees us from the toils of sin. Cheap grace is the grace we bestow on ourselves. Cheap grace is the preaching of forgiveness without requiring repentance, baptism without church discipline, Communion without confession, absolution without personal confession. Cheap grace is grace without discipleship, grace without the cross, grace without Jesus Christ living and incarnate."

Grace is costly, Bonhoeffer insists in contrast: "It is the pearl of great price to buy which the merchant will sell all his goods. ... it is costly because it cost God the life of his Son."

For Bonhoeffer, the logic of salvation is that grace, or mercy, has cost the life of the Son; therefore, the first act of a believer in response to the call of the Son is obedience, which has as its limit giving up one's life, following the Son.

He quotes the Gospel of Mark, "And as he passed by he saw Levi, the son of Alphaeus, sitting at the place of toll, and he saith unto him, 'Follow me.' And he arose and followed him" (2:14), and comments: "The call goes forth, and is at once followed by the response of obedience, not a confession of faith in Jesus."

"But how could the call immediately evoke obedience?" he asks, and his book in answer to this question says, in effect, that to have faith is to obey, and to obey is to have faith. The two are inseparable.

I encourage you to read Bonhoeffer's classic. But you may be wondering, as a Catholic, how trustworthy his teaching is. Yet the same teaching is found in the writings of a Catholic saint, John Henry Newman, in his sermon entitled "Faith and Obedience." True, Newman preached that sermon before he became a Catholic. Yet he endorsed it entirely and repeated its message after he converted. We can take the combined insight of Bonhoeffer and Newman to represent a convergence by devout souls on a fundamental Christian truth.

Newman for his part begins with the verse, "If thou wilt enter into life, keep the commandments" (Mt 19:17). "Let a plain man read the Gospels with a serious and humble mind, and as in God's presence," he says, "and I suppose he would be in no perplexity at all about the meaning of these words. They are clear as the day at first reading, and the rest of our Saviour's teaching does but corroborate their obvious meaning."

"What is meant by faith?" Newman asks. "To have faith in God," he says, "is to surrender one's-self to God, humbly to put one's interests, or to wish to be allowed to put them into His hands who is the Sovereign Giver of all good." It is Bonhoeffer's "costly grace."

"Now, again, let me ask," Newman goes on, "what is obedience?" Is it anything different? "It is the obvious mode, suggested by nature, of a creature's conducting himself in God's sight, who fears Him as his Maker, and knows that, as a sinner, he has especial cause for fearing him... . He will look every way to see how it is possible to approve himself to Him ... And he will find nothing better as an offering, or as an evidence, than obedience to that Holy Law, which conscience tells him has been given us by God Himself."

Thus, faith and obedience are "one thing viewed differently," Newman concludes. "When Christ calls a man, he bids him come and die," says Bonhoeffer. Newman might say: when Christ calls a man, he bids him trust and keep his commandments, even unto death.

What follows from all this? Newman concludes: "If, after all, to believe and to obey be but different characteristics of one and the same state of mind, in what a most serious error are whole masses of men involved at this day, who are commonly considered religious! ... It is certain, however startling it is to reflect upon it, that numbers do not in any true sense believe that they shall be judged."

MICHAEL PAKALUK IS PROFESSOR OF ETHICS AND SOCIAL PHILOSOPHY AT THE BUSCH SCHOOL OF BUSINESS AT THE CATHOLIC UNIVERSITY OF AMERICA AND A MEMBER OF THE PONTIFICAL ACADEMY OF ST. THOMAS AQUINAS. HIS MOST RECENT BOOK IS "MARY'S VOICE IN THE GOSPEL ACCORDING TO JOHN" (REGNERY GATEWAY).

- Michael Pakaluk, an Aristotle scholar and Ordinarius of the Pontifical Academy of St. Thomas Aquinas, is a professor in the Busch School of Business at the Catholic University of America. He lives in Hyattsville, MD, with his wife Catherine, also a professor at the Busch School, and their eight children. His latest book, on the Gospel of Mark, is "The Memoirs of St Peter." His next book,"Mary's Voice in the Gospel of John," is forthcoming from Regnery Gateway.