I don't see why being both God and man is a requirement of being "truly able" to mediate a covenant between God and men. All of the bi-lateral covenants between God and humanity in the Bible have been mediated just fine with a human serving as mediator. Why is a God-man a needed requirement for the new covenant?
2nd question : I'm reading Mere Christianity by C.S. Lewis and skipped a bit ahead to the part about being begotten versus being created. I understand the difference between the two and the logic displayed, so the question is this :
What do Trinitarians believe are the difference(s) between being "begotten" and being "created," in the sense of not having existence, and now existing? How can a "begotten" Person in the Godhead be uncreated?