In a sense this is true. While we are moving along the path to the place where Christ is formed in us, we have His righteousness to cover our shortcomings. If we should die before we reach perfection, we are still saved by His imputed righteousness.
But this is not God's perfect plan for the believer. Paul wrote that he was waiting for the righteousness which is by faith in Christ Jesus.
Ga 5:5 For we through the Spirit wait for the hope of righteousness by faith.
Obviously Paul at that time was justified, but he was still pressing on and waiting for a different kind of righteousness - his own - not based on his works but on the works of Christ.
Php 3:9 And be found in him, not having mine own righteousness, which is of the law, but that which is through the faith of Christ, the righteousness which is of God by faith:
After all, when we come to Christ, we come to Him to be perfected BY HIM.
Heb 10:14 For by one offering he hath perfected for ever them that are sanctified.
Eph 2:10 For we are his workmanship, created in Christ Jesus unto good works, which God hath before ordained that we should walk in them.
Eph 5:25 ...even as Christ also loved the church, and gave himself for it;
26 That he might sanctify and cleanse it with the washing of water by the word,
27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.
What He presents to Himself is a church that has been conformed to the likeness of Himself. But make no mistake about it, it will be our own righteousness, which He has formed in us.
What Jesus thinks of the doctrine of imputed righteousness as it is commonly taught is not pretty. As it is commonly taught, it is used as an escape from the necessity of being holy and righteous ourselves. Vast multitudes of Hell bound 'Christians' are trusting in that doctrine for their righteousness. They will split Hell wide open.
I think that the Jews had a similar doctrine in Judaism, and Jesus addressed that doctrine in this encounter with the Pharisees.
Mt 23:25 Woe unto you, scribes and Pharisees, hypocrites! for ye make clean the outside of the cup and of the platter, but within they are full of extortion and excess.
26 Thou blind Pharisee, cleanse first that which is within the cup and platter, that the outside of them may be clean also.
Lk 11:39 And the Lord said unto him, Now do ye Pharisees make clean the outside of the cup and the platter; but your inward part is full of ravening and wickedness.
Surely the doctrine of imputed righteousness as it is commonly taught will pump Hell full of souls. Multitudes, multitudes are trusting that they don't have to obey God because they will have Christ's righteousness imputed to them.
But throughout the scriptures, the commandments to be holy, to be perfect, are directed to US. For God to give us commandment that we either can not do, or that does not need to be done makes God out to be a fool and a tyrant.
Mt 5:48 Be ye therefore perfect, even as your Father which is in heaven is perfect.
Eph 1:4 According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love:
Eph 5:27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.
1Pe 1:15 But as he which hath called you is holy, so be ye holy in all manner of conversation;
1Pe 1:16 Because it is written, Be ye holy; for I am holy.
Re 20:6 Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years.
Re 22:11 He that is unjust, let him be unjust still: and he which is filthy, let him be filthy still: and he that is righteous, let him be righteous still: and he that is holy, let him be holy still.
All of these verses indicate personal righteousness, not imputed. Let us not trust in Jesus righteousness to free us from obedience to God. Instead let us trust in Jesus righteousness to be formed in us so that we too can stand in righteousness before God.
Eph 5:27 That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.
Re 19:8 And to her was granted that she should be arrayed in fine linen, clean and white: for the fine linen is the righteousness of saints.
wm