This chapter looks at the fundamental role played by spirit possession in the religious experience of Paul and of his Christ groups. It begins with their doctrinal and specifically christological elaborations. Being “in Christ” is the idiom through which Paul expresses the experience of possession by a πνεῦμα, which is identified with the risen Christ and which, through its presence in them, grants to believers salvation from the eschatological wrath and the expectation of eternal life. For Paul, Christ has achieved the state of existence designated as πνεῦμα through his death and resurrection. This was an idea that was also shared by other early Christ groups, as is confirmed—albeit not without negligible difference—by an examination of a key section in the Shepherd of Hermas.