This comes after the Apostle has established that no form of righteousness is the righteousness of God, not civil or Mosaic or any other kind of human righteousness.
Note the emphasis by word-order. First - not working but believing on the One Who justifies the ungodly - his faith is counted - λογιζεται η πιστις αυτου - as righteousness.
How can anyone extract Objective Justification from those words? Easy Peasy - they isolate a part of a verse, because they are lummoxen driven by conformity, and informed only by their boastful stupidity.
One UOJist proved his mental distortions by saying that faith meant "believing that we are already forgiven," which moves the true object of faith - Christ - to the dogma of rationalistic Halle Pieties, a bad bargain.
10 How was it then reckoned? - πως ουν ελογισθη - when he was in circumcision, or in uncircumcision? Not in circumcision, but in uncircumcision.
11 And he received the sign of circumcision, a seal of the righteousness of the faith - σφραγιδα της δικαιοσυνης της πιστεως της εν τη ακροβυστια which he had yet being uncircumcised: that he might be the father of all them that believe - εις το ειναι αυτον πατερα παντων των πιστευοντων -, though they be not circumcised; that righteousness might be imputed unto them also - εις το λογισθηναι και αυτοις την δικαιοσυνην:
12 And the father of circumcision to them who are not of the circumcision only, but who also walk in the steps of that faith of our father Abraham, which he had being yet uncircumcised.
This rather small but concise section discusses in greater detail, lest anyone get this wrong. that righteousness does not come to anyone except through faith in Christ. The faith of Abraham was not that he would be the leader of a great nation, but that he would establish the line of people who would provide the Savior and believers as uncountable as the stars in the sky.
Gen 15:5 - ἐξήγαγεν δὲ αὐτὸν ἔξω καὶ εἶπεν αὐτῷ ἀνάβλεψον δὴ εἰς τὸν οὐρανὸν καὶ ἀρίθμησον τοὺς ἀστέρας εἰ δυνήσῃ ἐξαριθμῆσαι αὐτούς καὶ εἶπεν οὕτως ἔσται τὸ σπέρμα σου (arithmatic)
This is an interesting play on words - Abraham cannot count the stars in the sky, and how does God count someone righteous? With the same faith in the Savior as Abraham saw from afar. That is how righteousness is counted. Verse 6 - Abraham believed and it was counted as righteousness.
The Righteousness of Faith - The Name of the Formula of Concord article on Justification - FC III
Romans 4:13 For the promise, that he should be the heir of the world, was not to Abraham, or to his seed, through the law, but through the righteousness of faith.
14 For if they which are of the law be heirs, faith is made void, and the promise made of none effect:
15 Because the law worketh wrath: for where no law is, there is no transgression.
16 Therefore it is of faith, that it might be by grace; to the end the promise might be sure to all the seed; not to that only which is of the law, but to that also which is of the faith of Abraham; who is the father of us all,
How do people wander so far from the righteousness of faith? Like Jay Webber, they make the Pietist Rambach their theologian, rejecting Chemnitz on 1 Timothy 3:16. They imagine that the sex cult leader - with no degree - who led the Saxon Migration was a better theologian than Luther. Do not be shocked. The ELS picked a New Testament professor who had less training than his Bethany students with a college degree. The ELS loved Moldstad's UOJ so much that they made him pope.
Romans 4:17 (As it is written, I have made thee a father of many nations,) before him whom he believed, even God, who quickeneth the dead, and calleth those things which be not as though they were.
18 Who against hope believed in hope, that he might become the father of many nations, according to that which was spoken, So shall thy seed be.
19 And being not weak in faith, he considered not his own body now dead, when he was about an hundred years old, neither yet the deadness of Sarah's womb:
The emphasis in these verses is not unbelief, but the importance of faith. The Messianic Promise canceled his natural doubts about being a father, let alone the father of many nations, and Sarah being a mother at that advanced age.
20 He staggered not at the promise of God through unbelief; but was strong in faith, giving glory to God;
21 And being fully persuaded that, what he had promised, he was able also to perform.
22 And therefore it was imputed to him for righteousness. - διο και ελογισθη αυτω εις δικαιοσυνην
How does unbelief make someone a guilt-free saint - as the Kokomites claim? Could any illustration be more clear than this - and it ends reflecting the Genesis 15 passage again. Romans 4 rests upon Genesis 15, and Genesis 15 foreshadows the New Testament Church and Gospel preaching.
Romans 4:23 Now it was not written for his sake alone, that it was imputed to him - οτι ελογισθη αυτω
24 But for us also, to whom it shall be imputed, if we believe on him that raised up Jesus our Lord from the dead - αλλα και δι ημας οις μελλει λογιζεσθαι τοις πιστευουσιν επι τον εγειραντα ιησουν τον κυριον ημων εκ νεκρων
25 Who was delivered for our offences, and was raised again for our justification.
To inject the toxin of UOJ into this argument, one must wrench the previous argument away from the righteousness of Abraham's faith. Thus the pea-brains of Universal Forgiveness without Faith say "Raised for our salvation!" as if part of a verse makes sense without the entire argument, without Father Abraham, the Father of Nations, the Father of Faith.
Thus Paul concludes the Romans 4 argument with this transition to Romans 5 -
Romans 5 Therefore being justified by faith, we have peace with God through our Lord Jesus Christ:
2 By whom also we have access by faith into this grace wherein we stand, and rejoice in hope of the glory of God.
5 δικαιωθεντες ουν εκ πιστεως ειρηνην εχομεν προς τον θεον δια του κυριου ημων ιησου χριστου
2 δι ου και την προσαγωγην εσχηκαμεν τη πιστει εις την χαριν ταυτην εν η εστηκαμεν και καυχωμεθα επ ελπιδι της δοξης του θεου
And Now - A Word from the Biblical Illiterates Who Advocate Justification without Faith