The difference of what is positional and what is practical
The Lord often speaks of the believer in terms that are present yet are still to be accomplished. God sees the end from the beginning and does not see time in a linear fashion and it is sometimes expressed this way.
We can say we are now without sin in a judicial sense because we are in Christ, God has pronounced us not guilty and will not judge us as He will judge the world for their sin. But to say we are sinless in a practical sense of everyday living in a fallen world shows a self deception, of being unaware of our unperfected state as creatures. We are justified but we are still being sanctified. If we did not need to be sanctified we would be in the last stage, the conclusion of the lifelong process - glorification, where we are made sinless, immortal in the body now.
We are both Justified (a one time event) and sanctification (a life long process) begins with our justification, it is a daily conforms us to Christs likeness (moral likeness). This means we still sin and the Holy Spirit has work to do in us.
Rom 8:30 Moreover whom He predestined, these He also called; whom He called, these He also justified; and whom He justified, these He also glorified.
Phil 1:6 being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ.
The completion is to be glorified, which is the end result of our salvation- it is future glory of the believer. Many confuse the Doctrine of Sanctification with glorification. Sanctification is a continual work of the Holy Spirit in the believer to conform us to the image of Gods Son (1 Cor. 6:11 it begins, with our justification.) justification is always depicted as a one-time event that begins with our possession of salvation. Rom. 5:1 says, Therefore having been justified by faith, it is a past event. Glorification is a future event is also a one time event, it comes at the end of the sanctification process and occurs when we get to Heaven, either by means of death, rapture, or resurrection. We are then in an eternal state permanently righteous in our nature. The Bible states in Rom. 8:30 that we are already seated in heavenly places. It is a "done deal" from Gods perspective. Yet we still have to wait to be united with our body to be glorified.
Rom 8:17-18: and if children, then heirs-- heirs of God and joint heirs with Christ, if indeed we suffer with Him, that we may also be glorified together.
Gal 5:5 For we through the Spirit eagerly wait for the hope of righteousness by faith.
Col 1:27 Christ in you, the hope of glory.
All through Scripture it speaks of our hope, which is now and for the future event that finalizes our salvation.
Titus 3:7 having been justified by His grace we should become heirs according to the hope of eternal life.
1 John 3:2-3 Beloved, now we are children of God; and it has not yet been revealed what we shall be, but we know that when He is revealed, we shall be like Him, for we shall see Him as He is. And everyone who has this hope in Him purifies himself, just as He is pure.
This change is a specific day called the resurrection of the dead and the rapture of the living.
1 Cor. 15:51-52 Behold, I tell you a mystery: We shall not all sleep, but we shall all be changed -- in a moment, in the twinkling of an eye, at the last trumpet.
1 Thess. 4:13-17 I do not want you to be ignorant, brethren, concerning those who have fallen asleep, lest you sorrow as others who have no hope. For if we believe that Jesus died and rose again, even so God will bring with Him those who sleep in Jesus. For this we say to you by the word of the Lord, that we who are alive and remain until the coming of the Lord will by no means precede those who are asleep. For the Lord Himself will descend from heaven with a shout, with the voice of an archangel, and with the trumpet of God. And the dead in Christ will rise first. Then we who are alive and remain shall be caught up together with them in the clouds to meet the Lord in the air. And thus we shall always be with the Lord.
We have this hope in death, those who have believed and whose spirit are in the presence of the Lord will come back with Christ on that day He comes for their bodies and the living church saints. He descends from heaven with a trumpet blown and those who have died will have their bodies united with their spirit immortalized first, and we who are alive will also be transformed and united together with them, forever to be with our Lord. That is a promise that is our hope.