I am suggesting:
1: Christianity, from the outset, can be said to declare that a belief in 'Father, Son and Holy Spirit', and a baptism in the name of Father, Son and Holy Spirit are conditional upon entering the community. In that sense, there is a body of people who acknowledge One God, and yet in effect swear allegiance to 'Father, Son and Holy Spirit', yet do not see themselves as transgressing the First Commandment.
2: That Confession of Faith in the three: Father, Son and Holy Spirit, I refer to as 'Trinitarian'
from the outset, even though the term itself was not coined until the 2nd century, and the doctrinal definitions emerge much later – the idea of 'person', for example, emerged from Christological (not Trinitarian) questions of the 4th and 5th centuries – these later definitions often corrected erroneous ideas.
3: Therefore I propose that the Faith of the first centuries was Trinitarian
in spirit – Father, Son and Holy Spirit – whereas the Faith
according to the letter emerged over time.
4: I argue this on the basis that the object of Faith – Father, Son and Holy Spirit – remained the same, whereas the understanding of the nature of Father, Son and Holy Spirit changed significantly and in some senses radically – the Christian of the 1st century and the 5th make the same basic credal statements, and receive the same baptism, and harbour the same hope of salvation.
5: The later arguments regarding Father Son and Holy Spirit were not whether they were God, but rather how they were God, and how, in the light of that, each relates to the other.
6: This process, contemporaneous with a defence of that Faith from criticism from without (eg Justin against Trypho, Origen against Celsus), involved the Fathers utilising philosophical theory, language and lexicon which inevitable had the effect of shaping the argument – the Fathers being obliged to argue their case in alien terms, on alien ground, as it were. One might say pagan theologies of the Platonist and the Stoics had a head start over the Christian theologians. This process is not without risk, evident when the likes of Justin align too closely with alien ideas ('a second god') to make their case.
7: In time, the theory, language and lexicon was shaped according to a growing understanding and insight into the Faith and its promise, and so whilst the influence of Middle and later NeoPlatonism is evident, and will remain so because the pagan thinker is not necessarily wrong because they are not Christian, the final declarations with regard to Trinitarian doctrine had moved away from a dependence on Greek philosophy within its own hermeneutic into one uniquely Christian, and it is this which gives Trinitarianism its unique expression.
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The SEP states:
"No theologian in the first three Christian centuries was a trinitarian in the sense of a believing that the one God is tripersonal, containing equally divine “persons”, Father, Son, and Holy Spirit."
To which the response is 'of course not', because the discussion of 'person' and the distinction between 'nature' (Gk
physis Lt
natura) and 'person' (Gk
prosopon Lt
persona) did not occur until the 4th-5th centuries, actually driven by Christological debate.
It argues the vocabulary existed, but not the Trinitarian belief behind it.
I'd argue the other way round.
The term itself appears in the 2nd century, and applies to something already understood – it's clearly not introducing a new concept but naming an existing one – then the term is applicable to the belief of Christians of a triune Godhead, even if in its early iterations it is somewhat at odds with later definitions, and the later statements employed a vocabulary which had itself evolved.
BTW: There's strong evidence that
homoousios was a term adopted not from Plato, but from the Gnostic schools of Basilides and Valentinus, who drew them from the Hermetic literature of the day. Origen employed the term, but in no great detail. The term was deployed at Nicaea, then does not appear in debate for another thirty years ...
The SEP states Tertullian did not believe in a tripersonal God, but rather a "tripersonal portion of matter."
Quite. The SEP also states that Tertullian "strongly emphasizes that these are truly three; none of the three is identical to any other." Yet, at the same time, "They are “undivided” in the sense that the Father, in sharing some of his matter, never loses any; rather, that matter comes to simultaneously compose more than one being."
The idea of the Father 'sharing' without ever actually losing or 'giving away' points to a qualitative understanding of matter, rather than a quantitative. It goes on –
"The Father is one entity, the Son is a second, and the Spirit is a third. Nor are they parts of any whole... "
"Despite these fundamental differences from later orthodoxy, Tertullian is now hailed by trinitarians for his use of the term “Trinity” (Latin: trinitas) and his view that it (at the last stage) consists of three persons with a common or shared “substance”."
So very much
in essence the same Trinity as spoken in the 4th, 5th and following centuries, although different in substance as the technical lexicon underwent significant revision and redefinition.
He also argues that the three are not identical ...
Nor are they, but yet undivided.
It's about fundamental doctrinal differences.
The fundamental doctrine is a belief in Father, Son and Holy Spirit – the Father wills, the Son redeems, the Holy Spirit sanctifies ... there's a Trinitarian belief from the Apostolic Era.
If Trinitarian belief was already present "in everything but definition," these struggles would not be necessary.
The struggles were, and are, all about the definition of relation.