Heavenly Participation is a book of evangelical ressourcement. Its basic argument can be seen as a popularisation of that of Boersma's Sacramental Ontology and Nouvelle Théologie: A Return to Mystery: with the theologians of la nouvelle théologie as their guides (pre-eminently de Lubac) readers are invited to ressource the Great Tradition – and indeed participate in it – by embracing its sacramental, or participatory ontology. For Boersma, participatory ontology is encapsulated in the notion that earthly realities are to be affirmed on account of the fact that they participate in heavenly ones, and it is this specific notion he seeks to commend (pp. 7–8).

Heavenly Participation is divided into two halves. The first traces the gradual eclipse of the patristic and early medieval participatory ontology in the High Middle Ages, Late Middle Ages and the Reformation. The second cuts short this genealogical approach with a systematic discussion of theological loci. Here Boersma asks readers to consider the transformative implications of participatory ontology for our views of the eucharist, time, biblical exegesis, truth and the discipline of theology. Boersma's argument, however, is not merely that the embrace of a participatory ontology will alter what Christians believe. It will alter the way they pursue the theological task and, ultimately, the way they live. For Boersma, the theological task must be reconfigured in sacramental terms – not as the mastery of truth but as initiation into mystery – if theologians are to capture and instil in their students the proper reciprocal and cyclical engagement of contemplation and action (p. 184).

To dismiss Boersma as an antiquarian with a fondness for things patristic is to misunderstand his proposal (p. 9). For Boersma, what distinguishes the Great Tradition from modern Christianity is its overwhelming sense that reality is pregnant with the mystery of Christ, and the theology of the Great Tradition (and particularly its exegesis) is to be embraced only inasmuch as it represents a ‘cashing in’ of this conviction (p. 129). Boersma agrees with his detractors that theologians of the Tradition sometimes failed to give adequate weight to earthly realities due to their overwhelming emphasis on heavenly ones. He insists, however, that the dominant trajectory of the Tradition steers a middle course between this caricatured vision of ‘pie in the sky’ and the reification of nature – the position Boersma identifies as his primary target. It is here that Boersma specifically addresses a young evangelical readership, readers Boersma identifies as increasingly passionate to engage in social action and creation care. Boersma's fear is that such initiatives are often motivated by an underlying desire to affirm creation ‘in and of itself’, which amounts to reification: creation becomes an idol when it is affirmed apart from its relationship to and dependence upon God (pp. 29–30).

But Heavenly Participation is to be considered a programmatic example of evangelical ressourcement, not merely because of its intended audience – indeed much of the work appears equally to address Roman Catholics. Nor is it to be considered evangelical because of a narrow confessional perspective. Boersma writes as an evangelical, but his vision is ecumenical. He proposes that evangelicals are able – as are all Christians – to bind themselves to the larger Tradition, and strengthen it, through their appropriation of its participatory ontology (p. 10). The book, then, is – in the first sense – evangelical because it is ressourcement. The heartbeat of ressourcement – as the nouvelle theologians conceived it – is the notion of going back in order to go forward, scholarship for the sake of the Church, for the sake of the world: for the sake of the gospel.