Previously on Paul. Not much time today. I'm off to Montreal as an observer at the biennial Association of Theological Schools meeting. We (Wesley Seminary at IWU) will apply for associate membership at the next meeting, Lord willing. On Friday the question of adjusting residency policies will be introduced. Currently the standard is two years, although some established schools like Asbury have an appropriate exception to require only one year. This is the direction I believe ATS needs to go for seminaries and the MDIV degree itself to revive and thrive. I am fairly confident this will be the decision at the next meeting.
So the idea that everyone has sinned at some point in his or her life was not a new idea Paul came up with. Mainstream Jews would have completely agreed with Paul on this point, not to mention his Christian opponents.  Mainstream Jews would have completely agreed with Paul that it was only because of God's grace that Israel enjoyed the special relationship with God they had. They did not earn this special relationship even if God expected them to keep the Law to maintain it. And even if specific Israelites might fail him, God would preserve a righteous remnant within Israel forever.
The disagreement thus was not that "all have sinned" but on what the implications of that sin were and on what God in his righteousness was doing to address that sin. In a nutshell, Paul argued that Jewish sinfulness was no different from Gentile sinfulness, that Jews did not get a pass on their sins simply because they were Jews. Even more importantly, God had determined only one way to make things right with him, and it was not keeping the Jewish Law. The faithful death of Jesus Christ was the only way God was accepting at this time.
Paul spends almost the first three chapters of Romans spelling out the problem and implications of the fact that "all have sinned." After the usual introductory material of 1:1-15 and the key verses of 1:16-17, Paul dedicates Romans 1:18-3:20 to the sin problem of humanity both for Jews and non-Jews alike.  The very familiar verse Romans 3:23 sums up this entire section: "All have sinned and are lacking the glory of God." 
 For example, one Qumran hymn says, "What is flesh compared to this? ... He is in iniquity from his maternal womb, and in guilt of unfaithfulness right to old age" (1QH12.29-30).
 The "prescript" or greetings of Romans are in 1:1-7. Then the "thanksgiving" section continues at least through verse 15, where Paul thanks God for the Romans. 1:16-17 are then the key verses of the letter.
 My translation.