Christian Teachings on Sex, Contraception and Natural Law

Why sex matters in Christianity

Christians generally understand sex as a gift from God, rather than something shameful in itself. It can express love, deepen a couple's relationship and bring new life into the world. Because it involves people's bodies, emotions and responsibilities towards possible children, Christians believe it should be treated with respect.

Two biblical teachings help explain these purposes. Genesis 2:24 describes a husband and wife becoming “one flesh”, suggesting a deep union rather than merely a physical act. Genesis 1:28 commands humans to “be fruitful and multiply”, linking sexual relationships with procreation: having children.

Traditional Christian teaching places sex within marriage, where lifelong commitment and faithfulness provide a stable setting for intimacy and raising children. Hebrews 13:4 teaches that marriage should be honoured and the marriage bed kept pure. Paul also describes the body as a “temple of the Holy Spirit” in 1 Corinthians 6:19–20. Christians can understand this as a duty to honour God through respectful, self-controlled sexual behaviour.

Some more liberal Christians accept sex within a committed, faithful relationship even when the couple are not married. They emphasise the quality of the relationship and the loving treatment of each person. The disagreement is therefore partly about whether marriage is an essential condition for sex, not simply about whether love and commitment matter.

Contraception and responsible parenthood

Contraception means methods or precautions used to prevent pregnancy. It can help couples plan the number and spacing of their children. Reasons for family planning include protecting a mother's health and ensuring that parents have the time, money and emotional resources to care for their children.

Artificial methods include condoms and hormonal methods such as the contraceptive pill. Natural family planning, or fertility awareness, involves identifying fertile times in the menstrual cycle and avoiding sexual intercourse at those times if pregnancy is not wanted. This requires careful monitoring and periods of abstinence. It does not protect against sexually transmitted infections; condoms can reduce the risk of transmitting infections such as HIV.

The Bible does not give a direct rule about modern contraception. Christians therefore apply broader teachings about creation, love, marriage and responsibility. Different interpretations of these teachings help explain why Christians reach different conclusions.

Aquinas: discovering God's purposes through reason

Thomas Aquinas was a medieval Catholic theologian and philosopher. His approach, Natural Law, holds that God created the world with purposes which humans can understand through reason. Morality involves living in accordance with those purposes. Here, “natural” does not simply mean avoiding manufactured products: it concerns what human life and human capacities are for.

Aquinas' five primary precepts are commonly summarised as:

1. Preserve life.
2. Continue the species through reproduction.
3. Educate children.
4. Live in an ordered society.
5. Worship God.

These are basic principles for human flourishing. Secondary precepts are practical rules worked out from them. For example, the duty to educate children can lead to rules about parents providing care and guidance.

The second primary precept is especially important for contraception. If reproduction is a God-given purpose of sex, deliberately blocking that purpose can be judged morally wrong. This provides a Natural Law argument against artificial contraception. It is not a claim that every person must have children or that every sexual act must produce a pregnancy.

An absolutist approach holds that certain actions are always right or wrong. Applied here, deliberately making a sexual act closed to procreation is judged wrong even when a couple believe that contraception would have beneficial consequences.

Official Catholic teaching: unity and openness to life

The Catholic Church teaches that sex within marriage has two inseparable purposes: it is unitive, strengthening the love of husband and wife, and procreative, remaining open to new life. Artificial contraception is rejected because it deliberately separates these purposes.

Pope Paul VI reaffirmed this teaching in Humanae Vitae in 1968. Each act of marital intercourse should remain open to the possibility of life. This does not mean that sex is forbidden when pregnancy is naturally unlikely: openness to life is different from guaranteeing conception.

Catholic teaching also recognises responsible parenthood. Couples may have serious reasons to space births, and natural family planning is permitted. The moral distinction is between choosing not to have sex during fertile periods and intervening to prevent conception during a sexual act. Although both may aim to avoid pregnancy, Catholic teaching regards the means used as morally different.

Supporters argue that this protects the integrity of sex as God's gift and prevents moral rules being changed simply for convenience. The Church also warns that separating sex from responsibility for children can encourage casual sexual behaviour. This is a concern underlying the teaching, not an inevitable outcome of using contraception.

Why other Christians reach different conclusions

Many Protestant Christians accept contraception within marriage as part of responsible parenthood. At the 1930 Lambeth Conference, the Church of England accepted that contraception could be morally permissible within marriage in certain circumstances. Acceptance does not mean that every use is considered responsible or that all Protestants agree.

Supporters emphasise that sex expresses love and intimacy as well as enabling reproduction. They argue that contraception can help parents protect health and provide proper care for existing children. They also point out that the Bible does not explicitly forbid contraception.

Some Christians use agape, selfless love, to guide decisions. Through situation ethics, they ask which action would be most loving in the particular circumstances. For a couple facing a serious health risk from another pregnancy, contraception might be understood as protecting life rather than rejecting God's gift of life.

Christians can also question how the primary precepts are applied. Preserving life and educating children may support planning births so that a family can care properly for its members. The dispute is whether these responsibilities justify artificial contraception, or whether they must be fulfilled only through morally permitted means such as natural family planning.

Individual Catholics may follow their conscience and use contraception because they consider it the most responsible choice. Their decisions should be distinguished from official Catholic teaching, which continues to reject artificial contraception.

Weighing the arguments

The central disagreement concerns both the purpose of sex and the basis of moral judgement. An absolutist Natural Law argument asks whether an action respects God's purposes, even when breaking the rule might produce benefits. A situation-ethics argument asks whether the action best expresses love in the circumstances.

A justified conclusion should address this difference. Someone defending Catholic teaching might argue that good intentions cannot make a wrong method right, especially when natural family planning is available. Someone supporting contraception might argue that protecting health and caring well for children fulfil important Christian responsibilities, and that preventing pregnancy need not undermine a loving relationship. A strong judgement explains why one consideration should take priority rather than merely stating a preference.