Robert Song's 2014 Covenant and Calling is oriented Toward a Theology of Same-Sex Relationships. I won't be talking about that here right now, but I do want to highlight one of the running threads throughout this book which--regardless of whether I'm persuaded by the book's overall argument or not--I find to be rather evocative and enlightening.
In the excerpts below I've tried to pull out and arrange the quotes that highlight this thread most clearly. It has to do with our understanding of marriage and family (or not-family) as particularly-discerned callings, the content of which is filled in by our primary covenant with Christ. I think you'll see there are all sorts of things one could talk about here (so let me know if you'd like to do just that).
'For the sake of clarity, in this book I will regularly refer to faithfulness, permanence and procreation as the [created] goods of marriage.
By faithfulness, I mean not just the commitment of the partners to forsake all others and stay faithful to the marriage bed, but also to provide mutual support, protection and love. By permanence is meant not an indissoluble, sacramental bond which makes divorce ontologically impossible, as found in Roman Catholic teaching, but the moral bond created by the promise of faithfulness so long as both partners shall live. By procreation I mean an openness to having children as the result of the couple's sexual relationship, mindful of the fact that not all marriages will in fact be fertile' (7).
Today's evangelical Christian typically views only the first two of these as essential to Christian marriage, but on Robert Song's observation still tends to construe 'childless marriages' according to a 'deficit model, defined by what they lack.' This leads him to ask: 'Might we not be able to imagine an alternative response to the place of deliberately childless marriages that hints at something altogether more constructive and hopeful?' (33).
'[I]f marriage is in part constituted by its procreativity and yet procreation is not possible, it is not clear what feature of marriage will ensure that such couples will be oriented to the good beyond themselves that is ordinarily embodied in children.Children symbolize, and in their demands on their parents they actualize, an openness to hospitality that prevents marriage collapsing into an egoistic and complacent coupledom' (34-35).
'Could [childless couples] also bear eschatological witness to the goods of faithfulness, permanence and fruitfulness, and thus participate in the corporate ecclesial discernment of vocation, in which some are called to bear witness to the goods of creation [via procreation], and others to creation's fulfilment in the coming Kingdom [via other kinds of fruitful hospitality]? (36).
'Might it be that after the birth of Christ covenant partnership is the deeper and more embracing category, with procreative marriage now being the special case?... All covenant partnerships would be characterized by faithfulness, permanence and fruitfulness, but in some cases that fruitfulness would take the specific form of children from within the couple's sexual relationship, in other cases it would take the form of any number of kinds of works of charity...
This would bring out the theological truth, and not just the moral exhortation, in Gregory of Nyssa's counsel that once children have left home and a couple's immediate responsibilities to them have died down, the couple themselves to works for the poor...
It would revivify the Christian understanding that marriages are always for something beyond themselves, not just for the personal fulfilment of the couple. Just as we saw that covenant partnerships must always be characterized by fruitfulness in doing the works of the Lord so as to avoid the dangers of an égoïsme à deux, so we would understand that procreative marriages are also always oriented to procreation as a species of fruitfulness and therefore oriented beyond themselves.
Marriages too carry the danger of forming introverted happy families, and need to be reminded that children are a good in themselves while also pointing beyond themselves, inasmuch as they are tokens of the hospitality and openness to the other that all marriages are called to.
The witness of the Christian Church in marriage would then clearly be demarcated not as a paeon to the nuclear family, let alone to patriarchal models of marriage, but rather to the avoidance of self-centred and consumerist models of marriage and family. Marriage enriches society and strengthens community, yet it does so not by raising new generations of consumers, but by nurturing people who are capable of love' (89-90).