The evolution of any book takes a meandering course: rising, often, out of the foothills of some other project; finding its own route through one's existing interests; winding out of familiar into increasingly unfamiliar territory until it arrives at an outfall on what may be quite an unexpected sea. One hopes then that the place will develop into a harbour, where new meetings can take place and new ideas be exchanged. I am fortunate that Roman Faith and Christian Faith has found its way to a new and multicultural space, where historians, biblical scholars, theologians, and philosophers can meet and exchange ideas of common interest.

Roman Faith arose from my existing interests in ancient history, biblical studies, and early Christianity, and particularly my interests in the history of mentality and the relationship between mentality, social practices, and institutions. It seeks to answer two interlocking questions: how do the attitudes and social practices encompassed by the language of pistis and fides (complex terms whose central meanings include ‘trust’, ‘trustworthiness’, ‘faithfulness’, and ‘good faith’) operate in the world of the early Roman empire? And within this world, why is pistis/fides (which in this context we often translate ‘faith’) uniquely important to early Christian communities?

The book begins by observing that the language of pistis/fides is central to Christianity as to no other ancient community and no other ancient or modern religious tradition. Without it, it is impossible to do justice to Christian understandings of the relationship between God, Christ, and humanity. Its importance, moreover, predates our earliest records. In Paul's first letter to the Thessalonians, dated to c. 49/50 and probably the earliest book of the New Testament in its current form, pistis language appears fourteen times in five short chapters, and followers of Jesus Christ are referred to as hoi pisteuontes as if the term will already be familiar to them. Thereafter the ‘pistis lexicon’ (pistis and all its cognates in all forms, as opposed to the ‘pistis lexeme’, which consists of forms of the noun pistis) appears throughout every book of the New Testament apart from 2 John, in every layer of redaction, and more often than any of the New Testament's other key concepts including love, righteousness, salvation, and hope.

It is therefore surprising that the reasons why pistis was so important to early Christians are almost unexamined. Biblical scholars and theologians take the importance of Christian faith, if not always its meaning, for granted (Morgan (Reference Morgan2015), 212–443 and passim), while classicists are interested in pistis/fides in the Greek and Roman worlds in general, but not among Christians. There is, however, prima facie a question to be answered, and it prompts another, closely linked: how did early Christians understand the meaning and operation of pistis/fides? It is only when we understand this that we can properly understand why pistis was so important to Christians.

To many theologians, axiomatically, Christian faith is, from its very beginnings, sui generis both as to its object, God's saving action in Christ, and as to its twin modes of operation: what Augustine (De Trin. 13.2.5) influentially defined as fides quae and fides qua (Morgan (Reference Morgan2015), 28–30). On this view Christian pistis/fides never shared its meaning, operation, or significance with pistis or fides in the world around it. This seemed to me most unlikely to be true. As I put it in what Professor Howard-Snyder, in a recent article, dubbed ‘Morgan's maxim’ (Howard-Snyder (Reference Howard-Snyder2017), 33),

Roman Faith set out to test the hypothesis that the meaning and operation of pistis in the earliest Christian communities, as evidenced by the writings of the New Testament, were very similar to those of pistis and fides in the contemporary Graeco-Roman and Jewish worlds, that Christians evolved new understandings and practices of trust or faith only gradually, and that any explanation of the importance of pistis to Christians must take this into account. The book took a ‘history of mentality’ approach: surveying the surviving literary, papyrological, and epigraphic sources of the period (c. 100 bce–200 ce) to identify large-scale patterns of thinking, and reading a large number of texts (including all the New Testament texts) closely, to identify distinctive ideas about pistis/fides in influential individual writings. To inform this approach it drew on recent writing in the sociology, anthropology, philosophy, economics, management theory, and modern historiography of trust, all fields in which important work has been published in recent years. Particularly stimulating was the idea, recently developed in anthropology and early modern history, that the shape of trust and related concepts and practices is unique to the community in which it operates, forming a distinctive pattern based on who trusts, or does not trust, or finds it difficult to trust, whom and what, on what grounds, and to what ends (Morgan (Reference Morgan2015), 22–23). The shape of pistis/fides in the different communities under scrutiny became one of the study's focal points.

After the Introduction, the first three chapters of the book discuss the Greek- and Latin-speaking societies of the late Hellenistic and early imperial worlds. They explore who trusted whom or what, and on what basis; when and why pistis/fides was easy or difficult to achieve; and, in the latter case, how fragile human trust could be deferred to more trustworthy objects or relationships (such as divinities) and how it could be reified into objects of shared trust (such as oaths or legal documents). These chapters discuss pistis/fides in oneself and pistis and fides relationships in the household, among masters and slaves, among friends, patrons and clients, in rhetoric, in gossip and hearsay, and in literary discourse; in the military, politics, inter-state relations, economic activity, in the law, at the foundations of states, and in times of crisis, and, last but not least, between human beings and gods. They conclude that pistis/fides was always important, but the degree to which it was seen as reliable varied significantly. Oneself and the evidence of one's senses, for example, are widely regarded as relatively trustworthy at this period. So, on the whole, are family members, including slaves, and experts in any field. Friends, in contrast, are rarely presented as wholly trustworthy, however desirable trustworthiness may be in principle – a source of detectable distress to many writers. Laws and magistrates attract perhaps unexpectedly strong trust, but kings and emperors little or none. Most strikingly, in almost every human situation, trust is to some degree fragile and contestable, cut with mistrust, doubt, fear, or scepticism. I explored the ways in which agents in the early principate sought to palliate the defects of pistis/fides by ‘deferring’ trust and ‘reifying’ it. For example, one might defer trust in a rumour to the production of evidence, or trust in a friend to proof, at some future point, of her goodwill. If my friend and I find it difficult to trust one another, we might reify the trust we wish to have in an oath, a credit agreement, or a legal trust: an object which we both find easier to trust than we do one another.

Chapter 4 deals with divine–human trust in Greek and Roman religiosity. It argues that there is more evidence for pistis/fides in Greek and Roman divine–human relations than historians usually assume. In particular, there is a certain amount of evidence that the gods are seen as trustworthy by human beings and that it is widely seen as appropriate that human beings should trust the gods. At the same time, the evidence of this period suggests that propositional belief in the gods is more difficult than trust, especially when one begins to examine the bases on which one might believe propositions. Of the bases for pistis/fides that are canvassed in our sources, personal experience (for instance in dreams or visions) and tradition are both treated as relatively secure. Reason and report are less so, and a persistent concern is detectable about the difficulty of detecting false beliefs. Above all, belief in the trustworthiness of the gods is based on foundationalist and coherentist claims about the nature of the world. As Cicero puts it in On the Nature of the Gods, the gods must be able and willing to help us, because if they are not, our piety is hollow and pointless, and if we abandon piety, justice, good faith, and society itself cannot stand (1.2.3–4). This is no cynical functionalist statement that religion shores up society. It attests, rather, Cicero's sense that his society's understanding of the gods and of itself are so intertwined that if it abandoned one it would lose both and collapse.

Greek and Roman religious thinking shares with Hellenistic Judaism another feature of divine–human pistis/fides: that human beings’ shared trust in the divine and its trustworthiness enables human beings to trust one another. This finding came into focus when it emerged, surprisingly, that it is not true of early Christianity. Christians are regularly told to love one another and live in peace with one another, but they are never told, simply as community members, to trust one another.

Outside the Septuagint and the works of Philo and Josephus, relatively little language of pistis/fides survives from Hellenistic Jewish sources. Philo's use of pistis is mainly in line with that of other Platonists in this period, and Josephus’ mainly in line with that of other Greek historians, so they are discussed alongside their Greek peers. Chapter 5, on the Septuagint, traces the evolution of pistis from the Pentateuch to the Hellenistic wisdom books.

In Genesis and Exodus, divine–human pistis can is presented as closely analogous to intra-human pistis, except that God is consistently trustworthy. Divine–human pistis evolves gradually, through initiatives of trust, doubt, assurances, proofs, and reifications of trust on both sides, to create new relationships which, over time, foster the development of the people of Israel. By the Hellenistic period, divine–human and intra-human trust are diverging. Trust in God becomes a non-negotiable obligation for human beings, even if it brings no positive consequences in their lifetime. Israelites’ main reassurance, if pistis needs one, lies in scripture and tradition, which affirm that God has never let Israel down, and the Deuteronomic law, which comes from God and confirms Israel's covenant with God. If the Lord sometimes seems distant, and trust in the Lord a challenge, the Lord's commandments provide a way of expressing daily one's trust and faithfulness towards God. These developments in Hellenistic Jewish pistis are significant not least as forming part of the immediate context of emerging Christianity.

The heart of the book consists of five chapters on the writings of the New Testament: two on Paul, one on most of the other epistles, one on the synoptic gospels and Acts, and one on the Johannine corpus. These offer close readings of all the New Testament passages in which pistis language occurs and extended engagement with the history of exegesis, which is dense and often conflicted. They discuss Christianity both in its own right, and as a rare example of a new community in evolution within the ancient world from which we have a rich insider perspective.

At the start of the project I was particularly interested in the overall shape of pistis in primitive Christian communities; where pistis is perceived as easy or difficult to enact, where it is cut with mistrust, doubt, fear, or scepticism, and the bases on which people put their trust or believed in God and Christ. By the end I was equally struck by the way different writers use pistis language to express the different ways in which they understand the nature and actions of Jesus Christ. In more than one writer an unsuspected connection emerged between pistis and predestination. Almost every writer presented some form of what I called a ‘cascade’ of pistis, flowing from God, through Christ and the apostles to community leaders and community members. This last finding liberates pistis from the silo which it has long inhabited as a ‘theological virtue’, making clear that it is not only theological but, equally significantly, ethical, shaping both divine–human relations and intra-human relations and social practices; ecclesiological, shaping the structure of primitive churches as institutions; and eschatological, shaping images of what the faithful hope for in the kingdom of God.

Among the themes which the book emphasizes are that throughout New Testament writings, pistis is more strongly relational than cognitive, a theme to which the following papers will return. It argues that the ‘cascade’ of trust not only gives the apostles their authority as preachers and baptizers, entrusted by Christ with the gospel (cf. 1 Thess. 2.4), but creates the earliest institutional structures of the church. It seeks to trace where Christians’ fascination with the concept and practice of pistis begins, and conclude that it may have derived in part (though probably not only) from the teaching of Jesus himself.

New Testament writers use pistis language in different ways to explore where to locate Christ, the new factor, in their inherited model of divine–human relations. John, for example, uses the verb pisteuein in passages that emphasize the identity of Christ with God: ‘Believe in God, believe also in me’ (14.1). The synoptic gospels use it when they want to emphasize the mobility of Christ between earth and heaven. People who come to Jesus to be healed, for instance, in the synoptic gospels, seem to approach what they see as a rabbi who can heal them, and encounter the Messiah who can also save them. Paul, meanwhile, draws on secular uses of pistis language in political diplomacy to locate Christ equidistantly between God and humanity as the one who reconciles them.

The argument draws a contrast between most New Testament writers, for whom pistis is an act of trust/belief based on their encounter with Christ, and John, for whom pisteuein is the act of recognizing that one has (already) been given eternal life and a response to that recognition. It also emphasizes that very early Christians show no signs of thinking of pistis as a deliberately non-rational ‘leap of faith’ in the modern, fideist sense. On the contrary, all the writers of the New Testament take some pains to explain (what they understand as) the firm bases on which people pisteuein: whether direct encounter with Christ, witnessing of miracles, or experience of the power of the Spirit.

Two final chapters draw the threads of Greek, Roman, Jewish, and Christian religiosity together to look at some areas where I argue they have much in common. All are more interested in the relationality of pistis/fides than its interiority. Interiority in faith, I conclude, developed as part of Christian pistis between the early second century and the fifth. Christianity also shares, together with classical and Jewish depictions of aboriginal and eschatological golden ages, Jewish and Christian visions of heaven, insider and outsider descriptions of some ‘elective’ Greek and Roman cults, and Stoic communities of good men, the feature that pistis, together with other ‘virtues’ or divine and divinely given qualities and practices, forms part of the structure of the remembered or hoped-for ideal divine–human society. Across the ancient Mediterranean, pistis/fides is structural to ideal socio-political collectives: foundational to the way people thought societies should be.

I hope this gives some flavour of the book. The articles that follow focus in more detail on some of the questions that arise from it.