The problem is, of course, that the apostolic church and early apologists were all subordinationist Unitarian. The claims of the Trinitarians are confined to the fourth century and, thus, it is convenient for them to confine the argument to the protagonists that were concerned with the Councils of Nicaea (325 CE) and Constantinople (381 CE).
The Arian view was not that of the early Unitarian subordinationists in that the School of Lucian of Antioch, which is the origin of the view, had two fundamental differences to Unitarianism (if the Athanasians can be trusted in their records, which is of itself problematic).
Schaff holds (ibid.) that:
The Arians made the Holy [Spirit] the first creature of the Son, and as subordinate to the Son as the Son to the Father. The Arian trinity was therefore not a trinity immanent and eternal, but arising in time and in descending grades, consisting of the uncreated God and two created demi-gods. The Semi-Arians here, as elsewhere, approached the orthodox doctrine, but rejected the consubstantiality, and asserted the creation of the Spirit.
We thus see that the Arians misapprehended the role of the Spirit and made it a creature of the Son when in fact the Holy Spirit was the means by which Christ could achieve his divinity. This is the fundamental distinction between Unitarianism and the view that is attributed to Arianism. The semi-Arians acquiesced in the question of the co-eternal co-equal son but held the Holy Spirit to be a creation of both. Thus, neither faction understood the early position of the Spirit as the power of God. These doctrines were as crippling to the faith in their way as Trinitarianism was in its way. The failure of the Arians to accept Revelation in the canon from the School of Lucian of Antioch no doubt contributed to their theological failure.
The semi-Arians are sometimes viewed as the first Binitarians. It is true that there were no early Binitarian groups in the church. Those that existed were originated by, and were allied with, the Gnostic elements that sought to eliminate the Old Testament and the Law, making Christ equal to God and superseding Him. The view that these semi-Arians were the first Binitarians thus places the doctrine in the fourth century and is termed the Macedonian faction from 362 CE. The problem with this view is that it was flawed and was an accommodation of the trinitarian view as developed from Nicaea in modification of the pre-trinitarian systems, either Arian or Binitarian. Neither view was correct. All three factions from Nicaea to Constantinople (325-381 CE) were thus wrong. The Council of Constantinople lost the semi-Arians in a walk out and thus the appeasement failed.
It must be remembered that the doctrines of these factions were wrong and they themselves, including the Athanasians (now Catholics), were unsure of what exactly the position was. As late as 380 Gregory of Nazianzen (or Nazianzus), one of the Cappadocians who advocated and developed the Trinity, made the remarkable statement:
Of the wise among us, some consider the Holy Spirit an influence, others a creature, others God [H]imself (oi de theon) and again others know not which way to decide, from reverence, as they say, for the Holy Scripture, which declares nothing exact in the case. For this reason they waver between worshipping and not worshipping the Holy Spirit, and strike a middle course which is in fact, however, a bad one (see also Schaff, fnn 5,6, p. 664). Basil in 370, still carefully avoided calling the Holy [Spirit] God, though with the view of gaining the weak. Hilary of Poietiers (sic) believed that the Spirit, who searches the deep things of God, must be divine, but could find no Scripture passage in which he is called God, and thought that he must be content with the existence of the Holy [Spirit] which the Scripture teaches and the heart attests (De Trinitate, ii, 29; and xii, 55; cf. Schaff, ibid.).
Schaff continues in this matter as follows:
But the church could not possibly satisfy itself with only two in one. The baptismal formula and the apostolic benediction, as the traditional trinitarian doxologies, put the Holy Ghost on an equality with the Father and the Son, and require a divine tri-personality resting upon a unity of essence. The divine triad tolerates in itself no inequality of essence, no mixture of Creator and creature. Athanasius well perceived this, and advocated with decision the consubstantiality of the Holy Spirit against the Pneumatomachi or Tropici (as the Macedonians were also called)
The real problem was that the doctrine had not been established. This view of Athanasius was adopted also by Basil, Gregory of Nazianzus, Gregory of Nyssa, Didymus and Ambrose (Schaff, ibid.). This doctrine was established from the Council of Alexandria in 362 AD, in Rome in 375 CE and finally in Constantinople in 381 CE.
Constantinople in 381 AD saw the exit of the thirty-six semi-Arians, Macedonians or Pneumatomachi. The council, after that exit, consisted of only 150 bishops (Schaff, op. cit., p. 639). It was thus unrepresentative of much of Christianity at the time. Schaff makes an assumption regarding the Nicaean Creed being ratified there (ibid.). It is, however, the first time that it appeared.
We can reasonably conclude that the Trinitarians were a Binitarian group that were manipulated by the Cappadocians to the next logical phase. Binitarianism is thus seen as the precursor to Trinitarianism and logically collapses to that doctrine over time. In these years, the new doctrine emerged from the effects of Gnosticism and Modalism on the church over the preceding centuries until it formed into the disputes of the fourth century.
The early and original position of the church was Unitarian and, hence, Subordinationist. It is not that there is no evidence on the matter. It is not an argument from silence. There is ample evidence and all of the evidence is Unitarian or heretical Modalist or Gnostic. The evidence precludes any Binitarian position among the apostolic or early church.