In light of the recent dustup over eternal subordination, I'd like to briefly recap and illustrate my own position:
1. When the Bible uses the theological metaphor of sonship for the second person of the Trinity, I think that metaphor is meant to evoke the principle of representation rather than derivation.
Representation involves two related concepts:
Like father/like son. A son is the same kind of being as his father. In addition, a son is more similar to his father than anyone else. In a sense, a son reproduces his father. You can see the father in the son. Not just at a physical level (family resemblance), but in terms of psychological commonalities.
A son can speak for his father. A son can act on his father's behalf.
(i) and (ii) are interrelated. Because a son is like his father, he's uniquely qualified to be his spokesman or agent. To act on his behalf and in his stead.
It's easy to document both these features in the mission of Christ.
2. Aside from the fact that I think the dogma of eternal generation lacks exegetical warrant, my theological objection to eternal generation is that it reduces the Son (and Spirit) to a shadow God.
Imagine a chain link fence on a sunny day. The sun is to my back. I put my left hand behind the fence. That casts a diamond-mesh pattern on my hand. I put my right hand in front of the fence, blocking the sunshine. The pattern on my left hand instantly vanishes.
That's like the Father producing the Son. The resultant pattern is entirely dependent on the source. Cut the transmission, and there's nothing left.
Suppose you say, to play along with the illustration, that the sunshine is uninterrupted. The sun necessarily shines on the fence, thereby casting a constant shadow on my hand.
But that doesn't change the absolute contingency of the shadow's existence. The radical asymmetry and irreversible directionality of the relation.
It's hard to avoid the conclusion that eternal generation (and eternal procession) makes the Father the real God, while the Son and Spirit are secondary effects.
3. I've discussed the exegesis of divine Sonship in detail, so I'm taking that for granted in my recap.