The first 15-20 years of Christianity’s spread – the most formative years – apparently took place without benefit of a single one of the New Testament documents we now possess. If the apostles’ message about afterlife could not be substantiated from the Old Testament, it could not be established at all, since their initial audience consisted of fellow Jews who would accept no other written authority.
The apostles’ account of Jesus and His resurrection was ultimately compelling to those Jews who believed them precisely because it matched the tapestry of Old Testament prophecies about Messiah and his times. If teaching about our Lord must be rooted in that source, is teaching about human afterlife to be grounded somewhere else?
(Note: These paragraphs first appeared as this comment on Randal Rauser’s blog post What in hell is going on? A Review of Sharon Baker’s “Razing Hell” (Part 3).)
Regarding human afterlife, see: Everyone Is Going to Heaven