Did Jesus' Resurrection Begin Christianity?

John Crossan in "The Birth of Christianity" asks why was Jesus' resurrection, as distinct from all other resurrections, considered as the beginning of Christianity? According to Crossan, during the early first century, the knowledge of resurrections was not not completely unique. Why wasn't Jesus' resurrection like that of Elijah, who was taken up individually to live with God. Crossman points out that Paul and others believed that Jesus' resurrection was considered the beginning of the end - the beginning of the general resurrection at the end of the world. (pp. xxviii - xix)