It is God that justifieth, Romans 8:33. None other can do so. For God alone is righteous. For he, alone, is God, Isaiah 45:24.
It is God who calls (sinners to repentance) and God who justifies them, Romans 8:30.
God is right because he is God. None other can be right, for he alone is God.
What and whom God is : is right.
It is 'rightness'.
Nothing else can be 'right'.
That which is in alignment, in agreement, in sympathy with God and with his purposes and with his desires : is right. And nothing else is 'right'.
That which agrees with his purpose in creation. That which is in alignment with his ultimate purpose in creating humanity, that is to say in alignment with the New Creation, in alignment with God's redemption, in agreement with his salvation . . . . is right.
Nothing else can be right.
The tree of the knowledge of good and evil is not the way for humanity to live. It is a way of death, Genesis 2:17.
God alone is righteous : humanity believeth.
And Abraham believed God . . and there was evaluated to him unto righteousness. Genesis 15:6, Galatians 3:6, Romans 4:9, Romans 4:22, James 2:23.
Within Abraham's faith God saw his own righteousness (God's righteousness) and seeing that within Abraham was the righteousness of God, God logically evaluated that to Abraham.
It was not Abraham's righteousness. It was God's own righteousness.
But it was attributed to Abraham unto (εισ) righteousness.
αβρααμ επιστευσεν τω θεω και ελογισθη αυτω εις δικαιοσυνην (Galatians 3:6 TR undisputed).
Those who see in the declaration of the gospel that God has demonstrated his own righteousness at Golgotha, eradicating sins by the sufferings of his own Son, and eradicating sin itself by the death of Jesus of Nazareth, they who see (in the gospel, for the gospel is the power of God unto salvation, Romans 1:16, for therein is the righteousness of God revealed) they who see the righteousness of God demonstrated therein and do so believe in God (as did Abraham) then it is logical, it is sensible, it is absolutely right that God should justify such persons.
And he does justify them.
He does do so freely.
Without the works of the law, Romans 3:28.
They are justified from all things, Acts 13:39.
By the law, this was impossible, Galatians 3:21. For the law saith : he that doeth them (the commandments) shall live in them, Galatians 3:12. But the law is not of faith, Galatians 3:12, again.
Faith believes God. Abraham believed God. And God freely justifies them who believe in him, Romans 3:24.
It would not be right to do otherwise.
For none is right, but God.
And it is he, himself who is our righteousness, as it is written 'The Lord our righteousness' Jeremiah 23:6.
He justifies the ungodly, who believe in him. And, believing, they receive the Holy Spirit, who works within them to will and to do the pleasure of the Father, Philippians 2:13.
And thus are they sanctified.
They do not 'remain as sinners'. That is a completely wrong apprehension of the scripture. Nowhere are the justified expected still to be sinners.
They are saints. They are the sanctified.
They also do no iniquity: they walk in his ways. Psalm 119:3.
He that is born of God doth not commit (or 'practice') sin, 1 John 3:9.
They do not continue in iniquity. 'For his seed remaineth in him: and he cannot sin, because he is born of God, 1 John 3:9 again.
For God (the Holy Spirit) is within them and they cannot sin. He will not suffer them to do so. He will bring them out of it with chastening, with ministration, with instruction. He will not leave them in it.
For this is the will of God, even your sanctification, 1 Thessalonians 4:3.
For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would. Galatians 5:17.
The natural and sinful inclinations of the justified are overcome by the inward dwelling of God, himself, in the Person of the Holy Spirit, Romans 8:1. And his presence leads them, influences them and keeps them from evil.
He restoreth my soul: he leadeth me in the paths of righteousness for his name's sake. Psalm 23:3.
And he leads them into all truth, John 16:13 . . . . such as the truth of justification by faith.
All references are to the KJV/TR.