Teenagers are to be warned that sex before marriage is "ugly and destructive and will lead to misery and regret".
The warning is part of a pamphlet sent to every secondary school in the country, published by the conservative campaign group the Family Education Trust. It seeks to inform teenagers of what it calls the dangers of contemporary society, in which we have come to "expect and demand instant gratification", and tells them to learn the difference between true love and "physical attraction, infatuation or lust".
The pamphlet claims: "We have become impatient, and we suffer the consequences in terms of personal debt, emotional trauma, sexually transmitted infections and family breakdown.
"In the context of a faithful, lifelong marriage, sexual intimacy is beautiful and enriching, but where a sexual relationship is pursued to express passing feelings and emotions, it is ugly and destructive and will lead to misery and regret."
The trust's director, Norman Wells, said: "It has become the norm for young people to embark on a series of short-term casual relationships that all too often prove to be a training ground for divorce rather than for happy and fulfilling marriages."
Andrew Copson, the British Humanist Association's chief executive, criticised the pamphlet. "Abstinence-only sex education does not work," he said.
"The only way to prevent unwanted pregnancies, the spread of sexually transmitted diseases and unhealthy, unfulfilling relationships is good-quality sex and relationships education, which accepts the reality that young people will have sex, and that what we need to do is help them to do so safely."