Miranda Threlfall-Holmes has a thoughtful post on 'Sex and Marriage'. I suggest she both gets a basic issue in current debates (when is sex sinful and when is it not) and offers an answer which begs other questions (when love is present sex is not sinful ... but that begs many questions re marriage, including why marry at all).
Time does not permit a full analysis of this post (and, in any case, that could be conducted by engaging in the comments at the post itself). Rather I want to lodge my own question here re sex which has been catalysed by her post:
why - from the perspective of Scripture as God's voice intruding in human affairs - is sex sinful in some circumstances and not in others?
To give a mere sketch of where an answer might head: sex is a physical act between two human beings which is invested with meaning beyond the basic biological fact concerning a purpose of sex, the procreation of another human being; it is the investment of meaning concerning sex which leads to concepts of sex is sometimes sinful and sometimes not; and it is the question of who invests meaning concerning sex which lies at the heart of our debates, with particular attention being paid to the following possible investors: the state, society, church, individuals and individual coupls.