God alone is the fullness of Being; only He exists through Himself. All created beings give glory to God by their existence and reflect Him in the harmony and beauty of their being. Mount Kilimanjaro and the steppes of Siberia, the Amazon River and the Indian Ocean, the coral reefs of Australia and the vast reaches of the universe all give glory to God. Living beings give glory to God, moreover, by the very fact of their life: their movement, their development, their necessary inclination towards the perfection that is their due: from the simplest forms of life to the most complex.
The human being, however, is not just another being in the scale of creation: “Of all visible creatures, only man is ‘able to know and love his Creator’ (Gaudium et Spes, 12,3). He is the ‘only creature on earth whom God has willed for its own sake’ (Gaudium et Spes, 24,3)” (Catechism, 356). The difference that marks the power of being the origin of our free acts is a radical difference: it is an essential difference and not only one of degree.
The structure of the human being entails a composition of matter and spirit that forms one unique subject. Thus the human being is not a “juxtaposition of two opposing elements,” but the union of two co-principles in a single substance, so that “the human body shares in the dignity of ‘the image of God’: it is a human body precisely because it is animated by the spiritual soul, and it is the whole human person who is intended to become, in the Body of Christ, a temple of the Spirit (cf. 1 Cor 6:19-20; 15:44-45)” (Catechism, 364).
This ontological reality stems from our human nature and makes possible the human being’s capacity to know and love. Hence we can have dominion over the material world, be aware of ourselves, perceive that others are also a unique “I,” discover and draw close to God and love Him by choosing Him as our end, and direct our life to giving Him glory by fulfilling his Will.
Thus “God created everything for man (cf. Gaudium et Spes, 12,1; 24,3; 39,1), but man in turn was created to serve and love God and to offer all creation back to him” (Catechism, 358). In short, man was created by God as body and spirit in order to give Him glory by ordering all material and spiritual realities to Him in love.
Human dignity, racism, xenophobia and discrimination
“Being in the image of God the human individual possesses the dignity of a person, who is not just something, but someone” (Catechism, 357). That is why the relationship of the human being with the material world, with other persons and with God is unique, different from all other visible creatures: with the uniqueness of a subject who is capable of loving freely. Thus it is only the end for which man has been created – to love God and others – that explains the greatness of his being and constitutes “the fundamental reason for his dignity” (Catechism, 356).
This intrinsic dignity of the human person is the foundation on which the radical equality of all men and women rests. “Respect for the human person entails respect for the rights that flow from his dignity” (Catechism, 1930), a dignity conferred on man by the Creator.
Indeed, the quality of being a person, of being someone, is common to every human being. As is their origin, end and the means to attain it. One’s individual or social qualities, culture, age, health, etc., can change neither one’s condition of being a person nor the dignity this entails. Being a human embryo, being a child or elderly; having more or less education, wealth or social status; being healthy or ill; living in one place or another or in one historical period or another... any of these circumstances are present in each human being, but do not alter his or her condition as a personal being. The human being is a person simply from the fact of being human.
Moreover, the human being is an essentially relational subject, because the whole structure of one’s being has been “designed” for love, and love entails an inclination to a lasting relationship with God and with other personal beings. This provides a further foundation for the equality of every person, which should be expressed in respect for each individual and group of persons.
Discrimination, in contrast, can be defined as “selecting by excluding,” or as unequal treatment of a person or group on the basis of race, religion, politics, sex, age, physical or mental condition, etc. In other words, it is unequal, unjust treatment, not simply “differential,” in the positive sense of this term. To treat differently what is in itself equal is as unjust as treating different realities equally. Discrimination in this sense is never justified.
Racism is a way of giving priority to a specific ethnic group (a form of idolatry) which attributes superior qualities and exclusive rights to a specific race and considers other races as essentially inferior, less worthy and excluded from certain rights. It can also be expressed negatively, i.e. the exclusion of the respect and rights due to any person and to a whole group of people (e.g. anti-Semitism, contempt for gypsies, etc.; in short, the consideration of any race as inferior).
Xenophobia is “hatred, disgust or hostility towards foreigners.” It is also a negative and exclusionary selection (of the need to recognise human dignity and, where appropriate, of the recognition of fundamental rights). It is particularly serious when it is directed against the weakest, such as immigrants or refugees.
Any discrimination that eliminates or limits respect for life is also unjust: for example, by claiming the right to decide which life is worth living and which is not, or by placing requirements on a person’s right to respect in addition to the very fact of being a person (in terms of physical or mental disability, age or health, etc.). Equally unjust is discrimination that imposes duties or diminishes rights on the basis of any accidental difference: “with respect to the fundamental rights of the person, every type of discrimination, whether social or cultural, whether based on sex, race, colour, social condition, language or religion, is to be overcome and eradicated as contrary to God’s intent (Gaudium et Spes, 29,2).”
The anthropological dimension of sexuality
“Man and woman have been created, which is to say, willed by God: on the one hand, in perfect equality as human persons; on the other, in their respective beings as man and woman. ‘Being man’ or ‘being woman’ is a reality which is good and willed by God . . . Man and woman are both with one and the same dignity ‘in the image of God.’ In their ‘being‑man’ and ‘being‑woman,’ they reflect the Creator’s wisdom and goodness” (Catechism, 369).
The human person has a “sexual dimension,” which embraces and shapes the whole person. The human person “is” woman or “is” man in all aspects of their life: biological, psychological and spiritual. Radical equality comes precisely from the fact of “being a human person”: the difference lies in the “way” of being a person. Woman and man are “different presentations” of the same and unique reality of being a human person, ordered to a special communion.
Heterosexuality is based on the acceptance of the natural difference between female and male persons; it proclaims equality as persons and at the same time recognises the difference in the way of being a person. And, furthermore, it shows how this foundation of equality and difference makes possible a special inter-personal relationship, in which each one contributes and receives. This gives rise to a complementary enrichment and the possibility of forming a common principle of generation. The natural inclination between man and woman leads to a specific kind of love, conjugal love, which entails the gift and acceptance of each other precisely in what is different. Marriage is not a form of legitimised sexual cohabitation, but “conjugality,” that is, a bond of “co-possession” of each one over the other in what he or she is as man and woman, as husband and wife, as potential mother and father. This union, exclusive and permanent, is in turn required for the dignity of the children who may come and for their care and education.
Obviously, unequal treatment of women or men because of their sex violates the dignity of the human person. Positive differentiation of women (or, as the case may be, of men) is licit and legitimate when it is intended to address a specific situation or to redress an unjust inequality in a given social circumstance. And it is licit because it is an attempt to balance and make just a previously unjust imbalance.
Studies on gender differences have advanced in quantity and quality and have provided interesting considerations. Certain forms of gender theory point to a radical break between the reality of human nature as created by God and behaviour with respect to sexual differentiation. They argue that sex, as such, does not exist, but is a cultural construct. Naturally, from this perspective there is no need to consider equality between women and men, because the key difference [sex] does not exist as such. Only biological traits exist, but these are part of the “natural neutrality” of the human body and need to be put at the service of each person’s freedom: anything else would be discrimination and artifice. Hence the first alienation on the personal level, they claim, is to accept the “real difference” of women and men, which leads to the imposition of heterosexual marriage and the monogamous family as a necessary consequence. Abolishing this alienation also entails eliminating the tie between the union between a man and a woman and procreation, motherhood itself (which punishes women) and the kinship relationships that result.
According to this distorted viewpoint, the characteristics of the body are seen as being at the free disposal each one’s desires, and therefore are modifiable at every moment. I am what I decide to be according to my own present desires: no other variables are involved. I can have a body with masculine characteristics and yet feel myself to be a woman, or homosexual, or bisexual. I can want to be transsexual, etc. All possibilities are open and equally legitimate, since no objective reality exists that limits them. All of the above is contrary to the Church’s teaching on the very structure of the human being: the unity of matter and spirit, the meaning of sexed corporeality, the complementarity of men and women, freedom, commitment, conjugal love, the importance of the marital union and the family, etc.
As for homosexuality (male or female), it is an attraction, exclusive or predominant, towards persons of the same sex. It can stem from many factors, including the person’s psychological characteristics and biography. “The tradition [of the Church] has always declared that ‘homosexual acts are intrinsically disordered’ (CDF, The Human Person, 8). They close the sexual act to the gift of life” (Catechism, 2357).
“The number of men and women who have deep‑seated homosexual tendencies is not negligible. This inclination, which is objectively disordered, constitutes for most of them a trial They must be accepted with respect, compassion, and sensitivity. Every sign of unjust discrimination in their regard should be avoided. These persons are called to fulfil God’s will in their lives and, if they are Christians, to unite to the sacrifice of the Lord’s Cross the difficulties they may encounter from their condition” (Catechism, 2358).
The apostolic exhortation Amoris Laetitia underlines Christ’s unconditional love for all people without exception, and reiterates that “every person, regardless of his or her sexual orientation, must be respected in his or her dignity and welcomed with respect, taking care to avoid ‘every sign of unjust discrimination’ (Catechism, 2358; cf.Final Report, 2015, 76) and particularly every form of aggression and violence” (Amoris Laetitia, 250). Families too are specifically asked to “ensure respectful accompaniment, so that those who manifest a homosexual tendency can count on the necessary help to understand and fully carry out God’s will in their lives” (cf. Catechism, 277).
Moreover, the Church reminds people that “homosexual persons are called to chastity. By the virtues of self‑mastery that teach them inner freedom, at times by the support of disinterested friendship, by prayer and sacramental grace, they can and should gradually and resolutely approach Christian perfection” (Catechism, 2359). Hence the call to chastity that is addressed to all Christians also reaches them.
With regard to the alleged equating of homosexual unions with marriage, the Church’s teaching recalls that “there is no basis for assimilating or establishing analogies, even remote ones, between homosexual unions and God’s plan for marriage and the family” (Amoris laetitia, 251). This is not a prohibition by the Church or the imposition of a punitive measure. It is a question of pointing out that these unions cannot be equated with a conjugal union, nor is it fair to attribute the same effects to them: because in this case there is no conjugality (which requires the differential relationship of the sexes), nor can those who live together constitute a common principle of generation.
Catechism of the Catholic Church, 356-373; 1930; 2113; 2357-2359.
 The text of this point of the Catechism continues with these moving words from Saint John Chrysostom: “What is it that is about to be created, that enjoys such honor? It is man that great and wonderful living creature, more precious in the eyes of God than all other creatures! For him the heavens and the earth, the sea and all the rest of creation exist. God attached so much importance to his salvation that he did not spare his own Son for the sake of man” (Saint John Chrysostom, Sermones in Genesim, 2,1: PG 54, 587D – 588th).
 “These rights are prior to society and must be recognized by it. They are the basis of the moral legitimacy of every authority: by flouting them, or refusing to recognize them in its positive legislation, a society undermines its own moral legitimacy” (cf. Pacem in Terris, 65)” (Catechism, 1930).
 “O wondrous vision, which makes us contemplate the human race in the unity of its origin in God . . . in the unity of its nature, composed equally in all men of a material body and a spiritual soul; in the unity of its immediate end and its mission in the world; in the unity of its dwelling, the earth, whose benefits all men, by right of nature, may use to sustain and develop life; in the unity of its supernatural end: God himself, to whom all ought to tend; in the unity of the means for attaining this end;. . . in the unity of the redemption wrought by Christ for all (Pius XII, Summi Pontificatus, 3; cf. Second Vatican Council, Nostra Aetate, 1) (Catechism, 360).
 It is licit to view differently what is different; in this sense, one can speak of a “positive differential treatment” when the common good requires or advises special protection or favour for a particular group because of its weakness (age, health, etc.), or because of particular needs (immigrants, etc.), or because of the good that a particular institution represents for the common good (for example, with regard to marriage and the family, tax deductions, maternity leave, etc.). In legal terminology, this particular type of protection is called “favor iuris”: the favour of the law. Not only is it not unjust, but it part of justice, which requires “giving to each one their due,” and therefore being attentive to the differential features of inter-personal relationships in society.
 “Idolatry not only refers to false pagan worship. It remains a constant temptation to faith. Idolatry consists in divinizing what is not God. Man commits idolatry whenever he honors and reveres a creature in place of God, whether this be gods or demons (for example, satanism), power, pleasure, race, ancestors, the state, money, etc.” (Catechism, 2113).
 At the same time, we must accept – and love – the other person with his or her differences and freedom. And we must love them in this way even if they have opinions or judgments opposed to our own, even if they are wrong. And even if what they do is wrong: if there is no harm done to others, we can warn them of the wrong they do, but we cannot impose on them the good they should do. This tolerance is not relativism; it does not mean admitting that every judgment or conduct is of equal value because there is no such thing as truth or goodness. On the contrary, this tolerance is based on respect for the freedom of each individual (and of groups) and requires at the same time a commitment to spread truth and goodness. We hold to our judgements about acts, but we respect the freedom of the individual.
 “In no way is God in man's image. He is neither man nor woman. God is pure spirit in which there is no place for the difference between the sexes. But the respective ‘perfections’ of man and woman reflect something of the infinite perfection of God: those of a mother (cf. Is 49:14-15; 66:13; Ps 131:2-3) and those of a father and husband (cf. Hos 11:1-4; Jer 3:4-19)” (Catechism, 370).
 Sex, in the human person, does not reside only in genital features, nor is it merely a programmed and necessary impulse for the reproduction of the species, as in other living beings.
 “The body, which expresses femininity ‘for’ masculinity,” and vice-versa masculinity ‘for’ femininity, manifests the reciprocity and communion of persons” (Saint John Paul II, General audience, 9 January 1980, no. 4).
 The word “conjugal” comes from the Latin verb “coniugare,” which means “to unite.”
 John Paull II, when commenting on the creation of man and woman in Genesis 2:24, writes: “The body, which through its own masculinity or femininity right from the beginning helps both to find themselves in communion of persons, becomes, in a particular way, the constituent element of their union, when they become husband and wife (General audience, 21 November 1979, no. 3).
 “It has taken a great variety of forms through the centuries and in different cultures. Its psychological genesis remains largely unexplained” (Catechism, 2357).