Relationships and sex education (RSE), as set out in the recent Bill making RSE compulsory for all English schools, should be appropriate to the religious background of pupils. This paper suggests that this appropriateness is best found by gaining the best understanding about religious young people's lived experiences of relationships and sexuality. Our in-depth qualitative research with three Christian young men aged 17-18 from a large charismatic evangelical church in the Midlands region of England investigated experiences of romantic relationships, focusing on the 'ethical moments' in which Christian ethical principles of sexual abstinence are negotiated. By attending closely to both the theological and the non-religious discursive resources that these negotiations draw upon, we demonstrate the different ways in which abstinence becomes meaningful in study participants' lifeworlds. We conclude that a sex education based on ethics in practice might engage best with religious young people.