Although I do agree that we should be able to stop sinning, as the letters of John insist we should...
I don't like the last statementof yours, where you say "completely becoming Christ in our lifetime." God will forever be Father, Son, and holy Spirit, there will never be any additions our subtractions from God.
However, we are his children if we have holy Spirit within us, living in us.
Never the less, I believe that we can submit to the spirit of Jesus within us evermore perfectly if we learn to submit constantly to his control, the gift of the Spirit within us. We are like human vessels who are sanctified by the Spirit of God. Thus without his Spirit we are just human. We are never holy apart from God in us. Again, I believe as we grow in constant submission to the spirit of Jesus within us, we can be almost exactly like Emmanuel, Christ, the human who had emptied himself of all his innate Logos powers, and relied on Father and holy Spirit to empower him.
It is enough, and beyond all imagination how wonderful it is for us, to be made holy by Christ's redemptive acts. It is enough that we are God's begotten children who will one day live eternally in his presence filled with his divine life. But striving to submit to the Righteousness of God, who is Jesus Christ himself, is our calling and duty.