Greek philosophy made it all but impossible to reconcile the transcendence of God with a deity who created and ruled the world, with a deity like that portrayed in the Hebrew Bible. During the Second Temple era, that clash of visions was deeply troubling for Jews who wished to integrate into the Greek-dominated international culture.
Of the thinkers who tried to reconcile the systems, the best-known was Philo of Alexandria (25 BC – 50 AD), whose life overlapped with figures like Jesus and Paul. At first sight, Philo presents God in a way instantly recognizable to a contemporary Greek Platonist. He sees God as unchangeable, without name, without relation to any other being, and humanity cannot perceive him. Philo briskly rejected the Bible’s anthropomorphism, its description of a deity with hands or eyes, with a face and “back parts.” Such words were all symbolic and metaphorical expressions used by Biblical authors, and only a very simple reader would treat them seriously.
Having excluded God from the world, though, Philo used a Stoic concept to bring him back (and he often ran into serious contradictions in the process). God was transcendent, but also thoroughly immanent, a constant creative force in all things. As a would-be Platonist, Philo explained creation as the work not of a God separated from the world, but of divine powers or attributes.
The most important of these powers that lay between perfect Form and imperfect matter was the Logos, Reason, God’s “first-born,” which is equivalent to Plato’s creative Demiurge. The Logos concept also stemmed from Stoic thought, but it was current in other Greek schools. Again trying to integrate ideas from multiple traditions, Philo is quite confused about how his Logos relates to the divine Wisdom, and deciding which emanates from which.
It is difficult to read Philo without invoking Christian theology and especially the Prologue to John’s Gospel. We inevitably think of the word that was with God, and that was God. The actual influence of the one on the other remains open to debate, but it is not hard to find statements by Philo that seem to close to the Christian model. (That certainly does not extend to the extremely radical notion of the Logos taking flesh).
Philo demonstrates to an extreme degree the difficulties of merging Judaism and Platonism without creating another figure who is, in effect, another manifestation of God.
One important book on Jewish ideas relating to this theme is Alan Segal’s much-discussed Two Powers in Heaven: Early Rabbinic Reports about Christianity and Gnosticism (Leiden: Brill, 1977). I won’t engage with it here, except to note the existence of the debates.