Very well handled.
AHunter, it may surprise you but traditional theology is not too far from your position. Jesus is, according to orthodox doctrine, “the only begotten Son of God*,” and the heirship that His followers have in the Kingdom of God is “by adoption and grace.” But yeah, you, me, and the rest are sons and daughters of God, through His intervention of atonement.
As noted, the concept of “how God was in Christ” is one that evolved over the first century – the earliest Christians seem quite willing to leave it at an unexamined “God was in Jesus the Christ” without attempting to define how, when, why, or wherefore. It’s in this context that kniz’s “Greek christ” becomes clear – the Messiah was/is/will be the person who leads the Jews back to a truer relationship with God and/or freedom from oppression. (Chaim Keller can speak to this concept more fully than I.) Mashiach in Hebrew simply meant “anointed one” – i.e., the leader anointed by God to save and free his people. Saul, David and his descendents, and Cyrus of Persia are referred to in scripture by this title, with that proximate meaning. As the Messiah concept evolved, however, it came to mean one who intervenes supernaturally to lead and free the Jews on the great and terrible Day of the Lord.
For the early Christians, Jesus turned the idea upside down on its head. He fulfilled it, not by promulgating the Torah or leading a war against the current empire-in-possession-of-Israel (Rome at the time), but by teaching an inner lordship of God within one (“The Kingdom of God is within you”) and by dying the torturous death of a criminal.
Christos in Greek means precisely the same as mashiach in Hebrew – literally, “one who is anointed.” The Hebrew and Greek for Psalm 23 would suggest that the Good Shepherd anoints each member of his flock’s head with oil. Because, however, the Greek Christians came to identify Jesus with the Messiah concept, turned upside-down and inside-out, He became for them the Christ.
As for the OP, I think that the only overt Scriptural Christology is in Paul’s letters, particularly Romans, and in Hebrews (probably not Paul’s work). But the Gospels, notably John, indicate a claim to unity of purpose and some mystical identity with God to which Jesus does lay claim, and it is simply a matter of injecting how this could be so into a metaphysical framework that gives rise to the doctrines of orthodox Christianity.
It is worth noting, too, that the terms for godhood used in Classical times were just a trifle more nebulous and diffuse than what we’d stand for today. E.g., while Augustus or Tiberius the Emperor were not divine, his genius – indwelling tutelary spirit – was. This was no more a contradiction in terms to the Romans, nor a trespass on the rights of Jupiter, Neptune, and the rest, than a military man’s insistence on Bush’s identity as Commander-in-Chief is today either subversive of military cohesiveness or a bar to his active membership in the Democratic Party. (That analogy sucks, but it’s the best that comes to mind.)
