There are five possible theories: Christianity, hallucination, myth, conspiracy and swoon.
1 | Jesus died | Jesus rose | Christianity |
2 | Jesus died | Jesus didn't rise—apostles deceived | Hallucination |
3 | Jesus died | Jesus didn't rise—apostles myth-makers | Myth |
4 | Jesus died | Jesus didn't rise—apostles deceivers | Conspiracy |
5 | Jesus didn't die | Swoon |
There are no other possibilities.
"Myth" in this context means the resurrection stories are not historically true but are intended as narratives of morality and religious meaning; not lies, per se, since pedagogy was the intent, not overt deception.
This, too: "What did the Disciples See? A Closer Look at the Resurrection Appearances"