Forgive me, but my observation is that modern protestantism has this tendency to push everything to a flat binary. It produces an over-simplified theology, often to where it is no longer true or useful. The "once saved always saved" effect is a similar feature.
Sin and sins is another example - it actually plays into the similar flatness of salvation in the same framework. If salvation is this one and done saved from sins, then we need a binary condition of needing salvation to go with it. And bam, you have every being a sinner, and since it is binary, everyone is the same level of wretched sinner. But that's not the ancient faith.
Now - do all need a savior? Yes. But we need to talk both about what we're saved from and freed from what we're saved towards and those are not the same things.
At any rate, this is a very bad abuse of the text of Romans 3. As always with the scriptures we need to handle them carefully. Romans is not a theological treatise - it is an letter to a church, written in a particular place and time, struggling with an issue. That issue is the reintroduction of Jewish Christians back into churches after their expulsion from Rome, and tensions between Gentile Christians and Jewish Christians upon that return. The overall theme is unity, with admonitions and encouragement spoken to both groups separately and together.
Romans 3, then is talking about the kind of synthesis of the previous paragraphs where St Paul walked through sin and righteousness as works of evil regardless of the explicit knowledge of the Torah of God, and that merely being one of the people who have the Torah doesn't protect you from unrighteousness. Unrighteousness practiced by a Jew is still unrighteousness. And then we arrive to St Paul's quote of the Psalms - "none is righteous" etc. But what did he say before that? "Are we Jews any better off [than Gentiles]? No, not at all. For we have already charged that all, both Jews and Greeks, are under sin, as it is written..." What does "all" mean in Romans 3:9? He tells you - both Jews and Greeks.
So in this narrative, St Paul is saying that having the Torah doesn't make Jews righteous. He says that doing unrighteousness makes you unrighteous. And then that this applies to both Jews and Gentiles. At this point he quotes the scriptures . Which he immediately follows up by pointing out that some of the scripture he just quoted was explicitly pointed toward Israel, therefore it is speaking to the Jews - again affirming that "all" here is both Jews and Gentiles, and that the Psalm doesn't somehow not include Jews. After he says, even further (scandalously to the ears of the Jews) that merely doing the works of Torah will not make you righteous in God's sight.
Sooooo is St Paul making a particular theological point here, that each and every individual person has performed a personal sin? No! He is not! He's saying quite clearly that both Jews and Gentiles are in need of a savior, because having the Torah doesn't make you righteous (because the Gentiles can be a Torah unto themselves), and merely keeping the works of the Torah will not make you righteous (because the Torah brings knowledge of sin).
Then we can see and understand his conclusion - "But now the righteousness of God" - he was just talking about how it doesn't come from having the Torah or merely doing the works of the Torah - "has been manifested apart from the Torah, even though the Torah and Prophets bear witness to it - the righteousness of God through faithfulness in Jesus Christ for all who have faith."
"For there is no distinction" - i.e. distinction between Jews who have the Torah and Gentiles who do not - "for all have sinned" again all is both Jews and Gentiles "and fallen short of the glory of God, and are made righteous by his grace as a gift, through the redemption that is in Christ Jesus, to be received by faith."
Just to drive the point home he says - "then what becomes of our boasting?" "Our" here means "we Jews" and he includes himself in the group. "Our [Jewish] boasting [in the Torah] is excluded. By what kind of Torah? By a Torah of works?" he's saying - is there some other Torah of works on top of the Torah we already have? "No, but by the Torah of faith, for we hold that one is made righteous by faith apart from works of the Torah."
How do I know "all" means "Jews and Gentiles"? Because he says it one more - time - "Or is God the God of Jews only? Is He not the God of the Gentiles also? Yes, since God is one who will make righteous the circumcised [Jew] by faithfulness and the uncircumcised [Gentile] through faithfulness. Do we overthrow the Torah by this faith? by no means. On the contrary we uphold the Torah."
Now I want to be clear that doesn't make that theological point that each and every human has sinned individually true or not true, but it does mean that using this passage as a proof text for that and saying that St Paul meant it that way, drawn out of context, is a kind of category error.
And even further, St Paul's conclusion is that since all mankind has fallen into sin - even Israel / the Jews - the solution for the problem of unrighteousness is the righteousness of faithfulness to Christ, which is a grace given by Christ Jesus. And, the RCC teaching (I am not RCC and do not hold to it) absolutely affirms St Paul's stance here by explicitly saying that Mary the Theotokos is made righteous not through a personal grace or charism, but grace given by God, through faith in God. So whether you agree with the RCC teaching or not, it is incorrect to say that it is unscriptural and point to Romans 3 or any of the scriptures St Paul quotes as evidence.
