The truth about the human person and sexuality does not change even as prevailing ideology exalts “freedom without relation to truth,” the Vatican’s doctrine chief said at a conference on Friday.

Jesuit Cardinal Luis Ladaria Ferrer, prefect of the Dicastery for the Doctrine of the Faith, gave the opening remarks at a May 19-20 congress on Humanae Vitae, the 1968 landmark encyclical from St. Paul VI.

“The truth expressed in humanity does not change; even more precisely in the light of new scientific discoveries, its doctrine becomes more current,“ Cardinal Ladaria said. It prompts us to reflect on Pope Francis‘ apostolic exhortation Amoris Laetitia (The Joy of Love) to rediscover the message of Paul VI’s encyclical, he said.

“The encyclical Humanae Vitae addressed issues related to sexuality, love and life, which are intimately interconnected,” the cardinal said. “These are issues that affect all human beings in every age. For this reason, his message remains relevant today. Pope Benedict XVI expressed it in these words: What was true yesterday remains true today.”

The international conference “Humanae Vitae: The Audacity of an Encyclical on Sexuality and Procreation” was organized by The Jérôme Lejeune International Chair in Bioethics. It was held at the Patristic Institute Augustinianum, a small conference center close to the Vatican.

Cardinal Ladaria’s opening remarks gave an overview of the anthropology of man as presented by Humanae Vitae, contrasting it with the prevailing anthropologies in Western society today.

“The encyclical,” he said, “bases its doctrine on the truth of the act of conjugal love, the inseparable connection that God has willed and that man cannot break on his own initiative, between the two meanings of the conjugal act.”

“If man is capable of recognizing and interpreting the unitive and procreative meanings of the conjugal act, he will fulfill his own existence correctly and bring it to its fullness.”

Like the voice of the Church, he said, “we, too, in the midst of our world, are called to be a sign of contradiction, proclaiming with unity and firmness the truth of the human being, of love, of sexuality, and of life.”

The cardinal explained that rejecting the teaching of Humanae Vitae is not only a rejection of the immorality of contraception but also an acceptance of a “dualistic anthropology that sees in nature a threat to freedom and that considers that by manipulating the body the conditions of truth of the conjugal act can be changed.”

“For the encyclical, nature is not in tension with freedom, but gives freedom the meanings that make possible the truth of the act of conjugal love and allow its full realization,” he said.

The separation of sex from procreation has, he continued, both trivialized human sexuality and transformed society’s understanding of sexual identity and what sexual relations are, creating an inability to recognize the moral differences between the sexual union of a man and a woman and sex between two men or two women.

The cardinal said the idea that “my body belongs to me” reflects an instrumentalization and materialization of the body, thus making it an object to manipulate.

He called this a “reification” of the body and said it has led to a decrease in births and an increase in abortions.

Life has become manufactured, leading it to no longer be viewed as a gift but as a product, valued in terms of its utility, he said. “Quality of life thus becomes a discriminating concept between lives worthy of being lived and lives unworthy of being lived.”

The manipulation of the body is also present in gender ideology and transhumanism, which “both start from the premise that there is no truth that can limit the implementation of their ideological postulates,” Cardinal Ladaria said.

The cardinal highlighted that this “contraceptive anthropology” present in gender ideology again places freedom in opposition to nature.

“This exaltation of freedom without relation to truth makes both ideologies present desire and will as the ultimate guarantors of human decisions,” he said. “Therefore, the continuation of the phrase ‘my body belongs to me; I will do with it what I want’ is the expression of desire alone as the guarantor of moral decision. But it is precisely the human body itself that appears as an obstacle, as a limit to the realization of desire.”

Someone’s “personal identity is now based on his orientation, i.e., without connection to his own body and without relation to the body of the other, without relation to the opposite sex,” Cardinal Ladaria continued. “It is an anthropology that has separated the vocation to love from the vocation to fecundity.”

Humanae Vitae, instead, “proposes an anthropology of the whole person, an anthropology capable of uniting freedom with nature,” he said.

“Man is truly himself when body and soul form an intimate unity.”

Speakers at the Humanae Vitae congress included physicians, theologians, academics and priests from around the world. Catholic couples also gave testimonies about the joys and challenges of married love and openness to life.

Among the presenters were U.S.-based moral theologian Pia de Solenni; the president of Culture of Life Africa, biologist Obianuju Ekeocha; and the president emeritus of the National Catholic Bioethics Center, John Haas.

Haas is also an ordinary member of the Pontifical Academy for Life (PAL). Other ordinary and corresponding members of PAL who participated in the meeting were Jean-Marie Le Méné, president of the Jérôme Lejeune Foundation; Mounir Farag, founder and president of the St. Joseph Institute for the Family, Bioethics, and Pro Vita; Elena Postigo Solana, director of the Institute of Bioethics at Francisco de Vitoria University of Madrid; and Pilar Vigil Portales, OB-GYN.