On the Trinity, see John Owen's [Brief Vindication](https://ccel.org/ccel/owen/trinity/trinity.i.html)
For a brief response regarding Hellenism, see Michael Horton's [Hellenistic or Hebrew?](https://www.semanticscholar.org/paper/Hellenistic-or-Hebrew-Open-Theism-and-Reformed-Horton/8fc416fd8bf9c04b4f98af616d738a9e585f2a6d)
I don't see how Hegel comes into play at all. The Gnostics were dealt with soundly by Irenaeus.