"
Now, the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it - the righteousness of God through faith in Jesus Christ for all who believe. For there is no distinction: for all have sinned and fall short of the glory of God, and are justified by His grace as a gift, through the redemption that is in Christ Jesus, whom God put forward as a propitiation by His blood, to be received by faith. This was to show God's righteousness, because, in His divine forbearance, He had passed over former sins." --Romans 3:21-25
In this passage, I want to focus especially on the last clause: "In His forbearance, He had passed over former sins." By itself, it strikes us as strange, because it seems to suggest that God was unconcerned about sins that occurred before the coming of Jesus. In fact, some people claim that it means that the heathen, who had not known God's written law, unlike Israel, were not held accountable for what would have been sins, because those acts were done in ignorance.
That view is an egregious act of eisegesis, inserting the assumptions of dispensationalism into a text which says no such thing.
First, consider the wording of the clause itself. The dispensationalist claims that God overlooked actions which would have been sins, but weren't. Yet Paul says just the opposite. He doesn't say that God overlooked actions; he explicitly states that God overlooked sins. "For all have sinned and fall short of the glory of God" (verse 23). So, there must be a standard by which those heathen were judged, and Paul tells us what that standard was: "The righteousness of God has been manifested apart from the law, though the Law and Prophets bear witness to it" (verse 21). Paul makes a distinction between "law," marked here with a small "p," and the Law, marked by a capital "P." Thus, there has always been a moral code, reflecting the righteous nature of God, which, at a particular point in time, was written down through Moses. Therefore, the dispensationalist is wrong. The law did not begin with Moses; it was merely recorded by Moses. It is the same as the theory of relativity. Energy equals mass times the speed of light squared did not suddenly come into existence when Albert Einstein put it in writing! It had been true ever since the first day of creation.
Second, do we see God's not holding heathens accountable for their sins?
"'Arise, go to Nineveh, that great city, and call out against it, for their evil has come before Me... Arise, go to Nineveh, that great city, and call out against it the message that I tell you.' So Jonah arose and went to Nineveh, according to the word of the Lord. Now Nineveh was an exceeding great city, three days' journey in breadth. Jonah began to go into the city, going a day's journey. And he called out, 'yet forty days, and Nineveh shall be overthrown!' And the people of Nineveh believed God. They called for a fast and put on sackcloth, from the greatest of them to the least of them" (Jonah 1:2, 3:2-5). God sent His prophet to these heathens to warn them of their coming judgment. Judgment according to what? The dispensationalist has no answer, because he holds to his presupposition that the law was only for Israel. We could also consider the case of Sodom and Gomorrah. While God relented of His wrath against Nineveh, He did not against the Sodomites (Genesis, chapters 18 and 19).
Thus, we must conclude logically that the doctrine of the dispensationalist was not what Paul intended. Rather, consider the context: he isn't giving us a contrast between sinfulness and sinlessness; he is contrasting the coming of Jesus, against the previous age without Him. While the Law and the Prophets directed Israel to the coming Redeemer, such as seen explicitly in Job 19:25, the heathen received no such succor. The faithful in Israel had an object for saving faith, but the heathen had none, except for a few individuals, such as Ruth. That is the sense in which God overlooked their sins: He refrained from revealing to them a basis for forgiveness and restoration. Thank God that He has now done so!