You seem to have a basic confusion over who are the ‘good people’ in the Bible. The Bible declares all are equally bound up under sin and are equally guilty before God. Therefore, all require salvation by Christ who personally died for the penalty of their sin. In this sense the more wicked you are, the greater candidate you are for Christianity. The blood of Christ brings peace between sinners and God by his free loving kindness not by collecting the good people together, but by forgiving and collecting the bad people together by salvation. Salvation is not at all dependent upon any good behavior or lack of animosity on the part of those who are converted to Christ by faith.
“None is righteous, no, not one; no one understands; no one seeks for God. All have turned aside; together they have become worthless; no one does good, not even one.” The Holy Bible: English Standard Version. 2001 (Ro 3:10–12).
You also seem to think the Bible had a long-term view of treating the Jews as ‘God’s people’ as though he was not always planning to include the entire world into his salvation. God is not a racist. God planned to save the world by calling one physical race, from which a Messiah would be born, in order that the whole world might be offered salvation. Right from the beginning God called Abraham in order that through his seed, (i.e. the Christ) Abraham would be the genealogical source of a ‘blessing to many nations’. The fact that the non Jewish world has accepted the Jewish Messiah, vindicates that Jesus is how Abraham became a source of blessing to the world. There has been no other 'Jewish religion' received by the world. Only this one by faith in the Jewish Messiah, Jesus Christ. This is miraculous that what happened was predicted to occur so long ago.
I will multiply your offspring as the stars of heaven and will give to your offspring all these lands. And in your offspring all the nations of the earth shall be blessed (The Holy Bible: English Standard Version. 2001 (Ge 26:4)
The basic idea to Christianity is that Jesus was the long awaited ‘Jewish Messiah’ to extend the Jewish religion to the entire world. Therefore the good people are the sinners who have taken hold of this Savior, who forgives and frees them from their sins, through his dying love. This includes Jews, Romans, Chinese, etc. In this sense a Jew (a person separated to God) is not a Jew according to race but is a Jew inwardly, according to faith in Christ.
For no one is a Jew who is merely one outwardly, nor is circumcision outward and physical. But a Jew is one inwardly, and circumcision is a matter of the heart, by the Spirit, not by the letter. (The Holy Bible: English Standard Version. 2001 (Ro 2:28–29))
Basically race and moral dispositions have no relevance to our candidacy for Christianity. The only qualification is that we recognize we are all sinners and have faith that Christ died for our sins. The Romans were ideal candidates as they were clearly a wicked and violent part of human history. They were just the type of people God has great joy in forgiving, saving and making holy. We are also just that type.