'Resurrecting' this thread...
My understanding of being perfect is not having one spot or blemish. When we first accept Christ as our Saviour, we have searched our hearts and have asked Jesus to cleanse us from all we have done (sin), to that point. We are then spotless (made righteous). That is why the thief on the cross, or anyone who gains Salvation just prior to death, will see eternity. They have been made spotless and have not had time to sin again.
For those of us that made that conversion a while ago, alot has transpired in our lives, and because of our carnal nature, we fall into sinful behaviour now and then. The Holy Spirit convicts us of these transgressions, along with other hidden ones we didn't remember, and we ask for the cleansing blood of Christ to forgive us and therefore, make us spotless again. As we go along in our walk with God, we recognize temptation more readily, as the Holy Spirit reveals it to us, because we are gaining spiritual discernment. We nip these temptations before they become sin in our hearts by asking for deliverence from them. This is the process of sanctification and the perfection to which we are able to attain.
So, everyone who will meet in the air on that beautiful day, will have no unrepented, known sins on their hearts. Jesus changes our corruptible to incorruption because we are not able to stand in the light of His Glory with these earthly vessels without perishing and must be transformed... be given our immortal bodies.