The Jews experienced a number of changes in their basic beliefs about resurrection over the centuries. By the time of the second temple, they had quite a fragmented set of ideas on the subject. The Pharisees believed that there would be a general resurrection of believers at the end of time (and often did not believe unbelievers would rise at all). The Saducees believed there was no resurrection. Other Jews had brought in the Platonic belief that the body was inferior and was best shucked off to live as eternal spirits.
The pagans also had changed their beliefs on the subject. Before ending up at the Platonic solution, they went through centuries of believing the dead were at best half-spiritually alive, and that they would never rise again. The dead forgot everything they ever knew, and lived comatose lives of spiritual misery forever. Plato did come along, and he did change all that. He taught that the dead were forevermore spiritual, and that they were infinitely happier than they had ever been while trapped in their mortal bodies.
Given this matrix of Jewish conflict on the subject, and complete pagan denunciation of the mere idea of resurrection, how Christianity come to embrace the idea of resurrection with one voice and in complete agreement? Why did they alter the Judaism from which they emerged such that the resurrection would be of two parts (first Christ, and later all His brothers and sisters) and such that it encompassed the whole idea of the triumphant kingdom?
NT Wright's answer in The Resurrection of the Son of God is, because Christ actually, eternally rose from the dead.
Wright makes a number of points. Most emphatically, he declares that resurrection is not life-after-death. There is definitely life after death, though most gospel writers are fuzzy at best about what that life is like, but that is not resurrection. Resurrection is life after life-after-death. Resurrection is when a formerly alive person dies, goes on to experience life-after-death, and then is brought back to live again on this planet with a new body - a body that is both physical and yet transcends the abilities of the former body and is somehow spiritual too. Heaven, he states, is not where we spend our eternity. Heaven is a realm unimaginably near to our own, and that intersects with our own in a number of ways, and our resurrected bodies will be comfortable interacting with heaven even while they live here on earth.
Wright explores every pertinent ancient source on the subject of resurrection in general, and on Christ's resurrection in particular. When he has completed his argument, you have insight into the beliefs of first temple Jews, second temple Jews, intertestamental apocryphal books, ancient pagan philosophers, later pagan philosophers, Paul, other writers of epistles, gospel writers, extra-canonical gospels, other Christian aprocryphal books, classical heretics, and finally the gospels' easter accounts. His historical analysis concludes with a thorough exploration of "necessary and sufficient" cause. He demonstrates that Christ's resurrection is sufficient to cause a movement like Christianity to emerge, and furthermore that an event like the resurrection actually happening as described is most probably necessary for the Christian doctrine of resurrection to emerge.
Throughout the entire book he maintains a consistent level-headedness that is a delight to read, and grants his opponents reasonable dignity, even as he tweaks their noses from time to time.
I won't kid you. At 730 pages, this book is probably not going to float everyone's boat, but if you've ever wanted to make a serious argument that the resurrection proved Christ as God's Son, you need this book. Wright defines the argument much more closely than anyone else I've ever read. He will keep you from over-promising on the meaning of the resurrection while arming you beautifully to defend the points you actually end up staking out.