What is the Eighth Commandment? What are sins against truth?

Truth or truthfulness is the virtue which consists in showing oneself true in deeds and truthful in words, and guarding against duplicity, dissimulation, and hypocrisy. . . . Respect for the reputation and honor of persons forbids all detraction and calumny in word or attitude.

—CCC, nos. 2505 and 2507

You shall not bear false witness against your neighbor.

—Ex 20:16

The Bible teaches that God is the source of truth. Jesus not only taught the truth; he also said, “I am the truth” (cf. Jn 14:6). The Hebrew word for truth, emeth, refers both to truth in words and truthfulness in deeds. Jesus both personalized truth and spoke nothing but the truth.

When Christ stood before Pilate, Pilate asked Jesus if he were a king. In his reply, Jesus declared that his Kingdom was not political but spiritual; he had come to bear witness to truth. A spiritual kingdom is based on truth. Pilate could not understand Christ’s reply. Jesus reached out to him and offered him the possibility of change. Pilate could only say, “What is truth?” (Jn 18:38).

In our culture, relativism challenges our ability to tell the truth because it claims there is no objective truth. This attitude undermines the distinction between truth and lies; it leads to an environment of deceit. In such an atmosphere, even Christ’s teachings, based on divine truth, fail to persuade those whose trust in the possibility of objective truth has disappeared. This is the climate in which the Church needs to call people back to the reality of objective truth and to the link between doctrinal truth and everyday life.

Sins Against Truth

“Lying is the most direct offense against the truth. . . . By injuring man’s relation to truth and to his neighbor, a lie offends against the fundamental relation of man and of his word to the Lord” (CCC, no. 2483). People sin against the truth when they are guilty of ruining the reputation of another by telling lies, when they practice rash judgment, or when they engage in detraction (the unjust telling of someone’s faults), perjury (lying under oath), or calumny (telling lies about another).

Scripture is clear about the evil of lying. In the Sermon on the Mount, Jesus said, “Let your ‘Yes’ mean ‘Yes’ and your ‘No’ mean ‘No.’ Anything more is from the evil one” (Mt 5:37). This reminds us not only that we need to be truthful, but also that hypocrisy—saying one thing while doing the opposite—is a sin against truth.

In the Gospel of John, Jesus describes the devil as father of lies (cf. Jn 8:44). St. Paul discouraged lying: “Stop lying to one another” (Col 3:9); “Speak the truth, each one to his neighbor, for we are members one of another” (Eph 4:25).

Happily, history is filled with stories of people who valued the truth so highly that they were willing to die for it. St. John Fisher (1469-1535) and St. Thomas More (1478-1535) surrendered their lives rather than approve of the divorce of King Henry VIII or deny the truth that the pope is Christ’s appointed head of the Church. During World War II, Franz Jagerstatter, an Austrian farmer, refused to accept the lies of the Nazis, and he was martyred for his commitment to Christ’s truth. During the French Revolution, a convent of Carmelite nuns chose to ignore laws that disbanded their monastery and continued to live together as a community. They courageously went to the guillotine rather than abandon the truth for which their vows stood.

We can testify to the truths of our faith in our everyday living, especially when we come in contact with those who do not hold the fullness of faith taught by the Catholic Church. This is done by living out the responsibilities and implications of our faith, as well as by being prepared to dialogue with others on issues of doctrine and morality where differences occur. “Always be ready to give an explanation [of your faith] to anyone who asks you for a reason for your hope, but do it with gentleness and reverence” (1 Pt 3:15-16).

You can read more from the United States Catholic Catechism for Adults, order your own copy, or read questions about it at the United States Conference of Catholic Bishops website.

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