It is precisely the fact that Christ is both faithful to God and worthy of God's trust, trustworthy by human beings and trusted by them, that enables him to take those who pisteuein into righteousness (p. 274).
... the tripartite relationship between God, Christ, and humanity, putting Christ in the centre of a nexus of faithfulness, trustworthiness, and trust which runs in all direction between God and Christ, Christ and humanity, and humanity and God (p. 281).
I also developed a threefold theology through my book, A Theological Introduction to Paul's Letters (2011). Later, I tried to get this idea across with my other publications; for example, How to Read Paul (2021); Rereading Galatians (2019); and Rereading Romans (2019). But there is still a tedious road ahead, and I will continue to fight against the tyranny of faith in the field.
The following text comes from Morgan's site:
*fides quae creditur (“faith which is believed”) and fides qua creditur (”faith by which it is believed”).
Why is ‘faith’ (pistis, fides in the languages that dominate the classical world) so important to Christians? What did they mean by it and how did they practise it in early churches? Is Christian faith fundamentally different from divine-human pistis/fides in Greek and Roman religions or ancient Judaism, or essentially similar? And how (if at all) did Christian faith affect the practice of pistis and fides in Greek and Roman public life after Christianity became the state cult of the Roman empire?
Modern understandings of faith depend heavily on Augustine of Hippo, who defines it (De trin. 13.2.5) as fides quae and fides qua, belief in the body of Christian doctrine and the faith which takes place in the heart and mind of the believer. In 2015 I published Roman Faith and Christian Faith, which argues that the earliest Christians understood pistis/fides very differently. Faith was a relationship of trust and faithfulness between God and human beings, which also shaped relationships between human beings, the authority structure of churches, and the way Christians imagined the kingdom of heaven. Christians were unique in putting trust at the heart of their relationship with God and Christ, but their understanding and practice of pistis/fides were continuous with those of contemporary Greeks, Romans and Jews.
*fides quae creditur (“faith which is believed”) and fides qua creditur (”faith by which it is believed”).