The "dying-and-rising god" is a proposed class of deity who dies and returns to life, and it is among the most contested categories in the study of religion, the dispute being not about the individual figures but about whether the class is real at all.
The category was made famous by James Frazer in The Golden Bough (1890 onward), who grouped Osiris, Tammuz or Dumuzi, Adonis, Attis and others as vegetation deities whose death and return enacted the agricultural year, and who placed Christianity in that context. The argument was enormously influential on early twentieth-century literature and on popular writing about religion, and it remains the source of most general familiarity with the idea.
It has been substantially dismantled by specialists. Jonathan Z. Smith's article in the Encyclopedia of Religion (1987) is the standard critique, and it proceeds case by case. Dumuzi descends to the underworld and is replaced there by his sister for half of each year, an exchange, not a resurrection. Osiris is killed, dismembered, reassembled and does return to life, but he rules the dead and does not return to the world of the living, and the Egyptian texts are consistent about this. Adonis' resurrection is attested only in late sources, some of them Christian. Attis' return is likewise late and disputed. Smith's conclusion was that the category had been constructed by imposing a single pattern, and that the pattern was substantially derived from Christianity and then discovered elsewhere.
The subsequent scholarship has not simply accepted this. Tryggve Mettinger's The Riddle of Resurrection (2001) re-examined the Near Eastern evidence and argued that a small number of genuine cases, including Melqart and arguably Dumuzi, can be established before the Christian era, while agreeing that the sweeping Frazerian class is untenable. The working position among specialists is roughly that: the broad category does not hold, individual figures must be assessed on their own evidence, and such resemblances as exist are looser and often later than Frazer supposed.
The stakes are partly apologetic, and this is usually visible in how the question is argued in public. The claim that Christianity borrowed its central narrative from the mystery religions is a staple of popular polemic, and the specialist objections to the category are frequently cited against it. Readers should note that those objections were made by historians of ancient Near Eastern religion on evidential grounds and not as a defence of Christian originality, Smith was not making an apologetic argument, but that the debate is now conducted in both registers simultaneously, and the two should be kept apart.