Above we defined chastity as a 'virtue of self-possession. It is about integrating one's sexuality into one's whole life as a human person. Being chaste means not being controlled by biological urges. Rather these urges or 'passions' are integrated into one's self-understanding as a sexual being made in the image of God who engages with other sexual beings who are themselves made in the image of God. Being chaste means taking control of one's desires and energies and directing them to those goods that are most rewarding, most meaningful, and that most support one's own flourishing and the flourishing of others.' Consequently, the Catholic perspective also highlights a number of so-called 'sins against chastity'. In other words, these are actions and their associated intentions which involve choosing not to direct one's sexuality, including its emotional and physical components, to those goals or ends that are most good for human flourishing, both of oneself and of others. In addition to masturbation and fornication (sex before marriage), these include lust, prostitution, incest and rape. What follows quotes directly from the Catechism of the Catholic Church (para. 2351–2356) and should be seen in light of the foregoing discussions on chastity and what is truly good. Lust is disordered desire for or inordinate enjoyment of sexual pleasure. Sexual pleasure is morally disordered when sought for itself, isolated from its procreative and unitive purposes. Pornography consists in removing real or simulated sexual acts from the intimacy of the partners, in order to display them deliberately to third parties. It offends against chastity because it perverts the conjugal act, the intimate giving of spouses to each other. It does grave injury to the dignity of its participants (actors, vendors, the public), since each one becomes an object of base pleasure and illicit profit for others. It immerses all who are involved in the illusion of a fantasy world. It is a grave offense. Civil authorities should prevent the production and distribution of pornographic materials. Prostitution does injury to the dignity of the person who engages in it, reducing the person to an instrument of sexual pleasure. The one who pays sins gravely against himself: he violates the chastity to which his Baptism pledged him and defiles his body, the temple of the Holy Spirit. Prostitution is a social scourge. It usually involves women, but also men, children, and adolescents (The latter two cases involve the added sin of scandal). While it is always gravely sinful to engage in prostitution, the imputability of the offense can be attenuated by destitution, blackmail, or social pressure. Rape is the forcible violation of the sexual intimacy of another person. It does injury to justice and charity. Rape deeply wounds the respect, freedom, and physical and moral integrity to which every person has a right. It causes grave damage that can mark the victim for life. It is always an intrinsically evil act. Graver still is the rape of children committed by parents (incest) or those responsible for the education of the children entrusted to them.

From a Catholic perspective, abortion, that is the intentional direct termination of pregnancy by killing the embryo or foetus, is always morally wrong. The Catholic perspective affirms: 'Human life is sacred because from its beginning it involves the creative action of God and it remains for ever in a special relationship with the Creator, who is its sole end. God alone is the Lord of life from its beginning until its end: no one can under any circumstance claim for himself the right directly to destroy an innocent human being (Congregation for the Doctrine of the Faith, 1987. 5). This Catholic understanding goes beyond God's supposed rights to be the giver and taker of life. This understanding moves beyond opposition to abortion simply because one is Catholic. Rather Catholic understanding here is in a very profound way about our attitude to life and love and the way in which these attitudes shape us as persons, regardless of our religious belief. When we are asked, what kind of a person do you want to be, the answer for most of us is 'a loving person', and 'a just person'. Faced with an unplanned pregnancy from whatever situation, the question about what kind of a person one wants to be is crucial. Asking the question of oneself should help us to see that to be truly loving and just, one must support life and love, one must stand up for the dignity, the worth of all human beings. So, whenever and however a child is conceived, the man and woman involved are called upon to take responsibility as human beings for their actions and to stand up for life and love. That means respecting the new life that has resulted from their behaviour and finding the best solution for the new human person whom they are privileged to bring into the world. If we examine the realities of our contemporary society, the issue of abortion most frequently arises precisely in those contexts where the Catholic perspective on sexual morality has not been followed, such as in having sex outside of marriage or where a married fail to act in ways characterised by love, justice and in accord with Catholic understandings of love and intimacy. Indeed, it is precisely such irresponsible and unethical behaviour towards woman in the marriage context that fuelled the call for women to have control of their reproductive capacities, including the so-called right to have an abortion. But abortion here only addresses a symptom. The cause, namely unjust and unloving sexual relationships between men and women, even in marriage remains unaddressed. The Catholic perspective does not condone the objectification of women as 'baby-making machines' or as satisfiers of their husband's sexual urges, just as the Catholic perspective also does not condone the reduction of sexual activity to sexual pleasure. All relationships must be seen in light of God's will for life and love. That said, however, even in contexts of irresponsible behaviour (sex outside of marriage) or unjust and unloving behaviour (objectification of women, even in marriage), the Catholic perspective still prioritises the goodness of the life that results from these actions above the wrongness of the actions themselves. In other words, just because we might have done the wrong thing (or someone might have done the wrong thing to us), this does not entitle us to take the life of an innocent person.

In case of rape a Catholic perspective permits the use of means to prevent fertilisation where there is no danger of causing an abortion. The Catholic perspective, however, does not permit the abortion of an embryo already conceived. For this reason, it is very important that people seek help as soon as possible after the rape. The logic of the Catholic argument is as follows. Whilst contraception is not permitted in the case of a loving married couple because this would defeat the purpose of marriage, in the case of rape a very different relationship exists between the two parties. The woman who has been raped has not freely chosen to have sexual intercourse with her attacker and indeed has been violated against her will by an aggressor. A person is always allowed to defend themselves against such an attack. Preventing the possible fertilization of one of the woman's ova by the attacker's sperm is a legitimate part of this defence against the attacker. Therefore, medications which specifically work to prevent fertilization can be administered. What may not be administered are medications that have an abortive effect resulting in the destruction of an already fertilized egg, which is now an embryo. Once fertilization has taken place, the newly formed embryo is considered an innocent human life, a human being worthy of the same respect as all other human beings.