1.) Sanctification, is "completed righteousness", ....is already accomplished by us being "in Christ". This is the effect of the Blood Atonement. Its the eternal effect of "The Gift of Righteousness".
The Blood Atonement alone does not mean we have “completed righteousness” and it does not “complete” our sanctification. If that were so, all mankind would be saved, because the Cross unconditionally redeemed all mankind (1John 2:2, 1Tim 2:3-6, Romans 5:18) - even atheists, Satanists and serial killers are redeemed by the Blood Atonement - but not all mankind will be saved.
It sounds like you don’t know the difference between our REDEMPTION and our SALVATION. Our REDEMPTION was a one-time event - the suffering and death of Jesus on the Cross- it is unconditional and includes everyone - past, present, future. On the other hand, our SALVATION is conditional and is a process - a process that begins with the sanctification provided by the Cross.
You also need to understand that there is more than one source and form of sanctification. There is (1) the sanctification that comes from the Cross, (2) the sanctification that comes from baptism, and (3) the sanctification that comes from personal righteousness - ie, keeping the commandments (Romans 6).
1.) Sanctification, is "completed righteousness", ....is already accomplished by us being "in Christ". This is the effect of the Blood Atonement. Its the eternal effect of "The Gift of Righteousness".
The Blood Atonement is not what is meant by the term, “in Christ”. 1John 2:3-5 explains how “we may be sure that we are IN HIM” (v.5) - “And by this we may be sure that we know him, if we keep
his commandments. He who says ‘I know Him’ but disobeys his
commandments is a LIAR, and the TRUTH IS NOT IN HIM”.
To be “in Christ” is to love Christ, and we demonstrate our love for him by keeping his commandments:
“If you keep my commandments you will abide in my love” (John 15:9).
To be “in Christ” means to abide in Christ, and we do this keeping his commandments:
“If you keep my commandments you will abide in my love” (John 15:9);
“All who keep His commandments abide in Him, and He in them.” (1John 3:24).
Rev 14:12 concisely describes what is means to be “in Christ” - “the saints, those who keep the commandments of God and the faith of Jesus”.
This is the effect of the Blood Atonement. Its the eternal effect of "The Gift of Righteousness".
The “effect” of the Blood Atonement is not “eternal” for everyone - for those who reject the free gift of God’s grace through faith in Christ, the Blood Atonement has no effect at all - let alone an eternal effect - because they will not make it to Heaven.
So, until a person who is born again, sees themselves as GOD sees them
Believers who don’t repent of their sins are still unrighteous sinners in the eyes of God. In Gal 5 and 1Cor 6, Paul warns believers that that sins can result in them not inheriting the kingdom of God. If you disobey God and don’t strive (ie, attempt, albeit imperfectly) to keep his commandments, you may be judged to not be “in Christ” and may end up in Hell, as Paul warns (as does Jesus in Matt 7:21-23).
We must walk in the light by keeping his commandments (“
IF we walk in the light, as he is in the light … then the blood of Jesus his Son cleanses us from all sin” - 1John 1:7).
Christians are literally , right now, Spiritual citizens of Heaven
You forgot to mention that any Christian can lose his citizenship due to loss of faith or sin. But if you want to delude yourself that you’re already saved, go ahead - it won’t help you come Judgement Day.