We are accepted with God and placed in the shelter of Christ's righteousness before we gain total victory over our old nature. We can be reckoned righteous before we are righteous. We share in the righteousness of Christ before we become fully Chist-like. This is why I said at the beginning that this text is a word of hope for eanest strugglers. If there were no place in Christ for beginners and strugglers and stumblers then most of us would have given up long ago in despair.
Nobody is born mature.
Babies come before adults. The next thing to notice about the Corinthians is that they couldn't eat solid food buty only milk. Verse 3 gives us the key to the answers. In other words the evidence of being fleshly, or still in the baby stage, is jealousy and strife. Or to put it positively, the organ that properly digests solid food is humility.