Christianity was a radical movement in many ways. Its unique theology made it enough of an offense to warrant harsh skepticism but it was its erasure of class distinctions that made it especially grievous.
There is neither Jew nor Greek, there is neither bond nor free, there is neither male nor female: for ye are all one in Christ Jesus. (Galatians 3:38)
What is a wonderful and liberating statement today was a wholly radical claim to the ancients. The Biblical world was what is known as a collectivist society. Scholars Pilch and Malina note,
In contemporary American culture we consider an individual’s psychological makeup to be the key to understanding who a person might be. We see each individual as bounded and unique, a more or less integrated motivational and cognitive universe, a dynamic center of awareness and judgment that is set over against other such individuals and interacts with them. This sort of individualism has been and is extremely rare in the world’s cultures and is almost certainly absent from the Bible.
In the ancient Mediterranean world such a view of the individual did not exist. There every person was understood to be embedded in others and had his or her identity only in relation to these others who formed this fundamental group. For most people this was the family and it meant that individuals neither acted nor thought of themselves as persons independent of the family group. What one member of the family was, every member of the family was, psychologically as well as every other way. 
With this we can begin to understand how Paul’s statement in Galatians 3:28 would be received by the ancient world. The erasure and blurring of social distinctions would have made Christianity seem radical, rebellious, even offensive. Conversions such as those of Paul and James were highly abnormal and socially unacceptable. They would be, in essence, forfeiting their identity and the roles they were expected to fulfil.
Critics have argued that Christianity was/is a distinctly manipulative religion, wooing the poor in wealth and mind (in those times they would be slaves to some master) with false promises and phony love, appealing to those who desperately need it. However, this argument doesn’t quite have the same bite if we apply it practically.
The first problem is that, even if this were correct, it wouldn’t go far in actually changing their condition. Christianity would come to underhand slavery and abolish it from the inside out (The Martin Luther King approach we could call it). A brute, frontal attack on a well-established social system would have been the worst possible way to go about it.
The second problem is that critics assume that slaves would be always looking and hoping for a way out. This wasn’t the case. Malina, in Portraits Of Paul, notes that freedom for the ancients was defined as “freedom from slavery to one lord or master, and freedom to enter the service of another lord or benefactor.”  It would not have occurred to them that their situation could ever change, as Malina notes,
When faced with a crisis or significant problem, U.S. persons are expected “to do something about it.” Problem solvers regularly ask, “What can we do?” in response to a crisis or calamity. And they do not feel good about the problem unless they start doing something. Not so the ancient Mediterraneans….. they perceive themselves controlled by other persons, by sky beings of various sorts, and ultimately by God. Their roles and statuses are ascribed to them by God (1 Cor. 7:17; 12:18) and so belong to the order of creation and cannot be “uncreated.” Thus, they tend to face crises and calamities somewhat passively, expressing their understanding of events in terms of a doctrine of divine providence, fortune, or fate controlling all existence. 
When Christianity came to shatter these beliefs about identity and underhanded the established social system it would have been seen as a colossal faux-pas…..Unless there was something true behind it.
Likewise, the Jews would have had no place for such “nonsense” as their identity was bound to the law and their observance of the Torah. In comes the death of Jesus and suddenly the law is made obsolete. Just imagine. The thing that made the Jews who they were, the works they were proud to have accomplished, all that which determined their worth and honour in the sight of God, all counted as “dung”!
…..touching the righteousness which is in the law, blameless. But what things were gain to me, those I counted loss for Christ. Yea doubtless, and I count all things but loss for the excellency of the knowledge of Christ Jesus my Lord: for whom I have suffered the loss of all things, and do count them but dung, that I may win Christ. (Philippians 3:6-8)
It goes without being said that to the ancients this “Jesus Christ” must have, no, need have been more than a mere man for these claims to pass. In a collectivist society you took your identity from the leader of the group to which you belonged and much like us today they needed social support and endorsement of that group. But as we’ve taken greath lengths to explain thus far, Christianity did not have such social acceptance or endorsement.
The question is, what made Christianity more appealing than other far less offensive and non-divergent groups one could identifying themselves with? Perhaps a charismatic leader? The problem with this response is that charisma wasn’t typically seen as a sign of authenticity or reliability but more so of deviancy and foolishness.  Tradition and accepted values was the key in earning respect. Jesus, living in the law, followed and esteemed the law, but He would not have inspired loyal followers- leaving everything to follow Him-on charisma or moral teaching, contrary to what modern critics would argue (especially when it’s considered that many of Jesus’ teachings, such as leaving behind family and kinsfolk for the sake of the Kingdom or the theme of being born again, would have been offensive). Jesus gained followers because He was seen as a reputational teacher, gaining a both a controversial and awe-inspiring reputation through miracles, healings, exorcisms, and by winning honour challenges the Pharisees set against Him. If Jesus had been little more than a charismatic human He would not have lived up to expectations and His memory would have faded long before anyone wrote a single word about Him.
So we ask again, with what assurance would those who joined Christianity have that they were gaining life in return of death (i.e social persecution and ostracization) if the Resurrection were not true?
1. Pilch, John J.. Handbook of Biblical Social Values, Third Edition (Matrix: The Bible in Mediterranean Context 10) . Cascade Books, an Imprint of Wipf and Stock Publishers. Kindle Edition.
2. Bruce Malina and Richard Neyrey, Portraits Of Paul (John Knox: 1983), p. 163
3. Ibid, p.189
4. Williams Herzog, Prophet and Teacher