Actually, it is quite complicated to understand using the logical mind. It's highly esoteric. To hear someone say the Trinity doctrine is easy to understand, says to me they have begun to attempt to penetrate it. It's like I said in my post just now to popsthebuilder, we project our earth-bound reality using our language to attempt to describe the Infinite. How deeply or how little we understand the metaphorical nature of language, and how deeply or how little we allow ourselves to imagine beyond our highly restrictive finite realities, determines how much God looks just like us as we see ourselves in our reality. (That may take a minute to sink in a little).
Let me demonstrate the problem of your language here and what it projects onto the divine. You use the term "share in the same nature". That creates this image of say God and Jesus sitting in a swimming pool sharing the same water, or sitting at the same table and sharing the same wine. The problem with this is that you make the Father's nature outside of the Father, that both Jesus and he share in. This imagines two separate beings sharing something in common, and that something would therefore be something that exists beyond both of themselves. You make the nature of God something God himself shares in with Jesus, or with us.
There is no sharing. God IS. No beginning, no end, no boundaries. "In him we live and move and have our being", describes the reality of God and our reality fairly well to me. No boundaries in reality, only in illusion, the darkness of our own imaginations.
What you don't see in Paul's expression of Christ in Hebrews is that he does simply share attributes, he is the very expression of the divine itself. That's is considerably beyond sharing qualities. It is the very Manifestation of God itself, though Christ, through Logos. As Logos expresses the Divine, Logos is the Divine itself expressing, in expression, in manifestation, in revealing. There is no "sharing" which takes place with separate individuals. There is simply Manifestation of the Divine. That is what Paul is saying (as well as Gospel John). "The Son is the radiance of God’s glory and the exact representation of his being".
Paul speaks in terms of the distinction between the Father and the Son here is because he is trying to speak about who Jesus is to them. This man who lived among them, is the eternal Manifestor of God, the Creator of the world, become flesh and Manifesting God as man as he has as the eternal image of God, the power of God, the expression of God. God in flesh, revealing God as a man. This is exactly what John was saying about the Logos, who manifested God eternally, and how that the whole of creation was through this Manifestor, this Revealer of the Eternal into time. "All things were created by him." And then, John 1:14, "The Logos became flesh and dwelt among us". Jesus was the human embodiment of the Eternal Logos, continuing in human flesh what who and what he has always been since before the creation of this world.
Pause to let you process that.
