Nonetheless, we still have an old sin nature. This was not existant in our Lord and Savior Christ Jesus. The physical seed of such a man, likewise would not have to sacrifice the old man in order to find the kingdom of God.
This is a part that gives me pause. I find it almost unfathomable to think that as an adolescent, he did not sin (by thought, word or deed). Granted, I believe he asked for forgiveness daily; but if he had cast no sin; what would you beg forgiveness for? If he married, then sex is no sin; for are we not commanded to 'Go forth and multiply'? Is striking out in violence and physically rebuking another sinner a sin? Then, was Christ's (justified) outburst against the money-changers in the temple a sin? I think he lived the perfect life, in that he accomplished his goals, as only the Son of God could, but ascribing a sin-less quality is not scripturally represented. This is an attribute that has been attached to Christ by man.
Why would the off-spring of Jesus be considered 'perfect'. Granted, it's pretty hard to trump the lineage; but regardless of your ancestry, you have Adam and Eve to thank for the propensity to sin.