@Reggie_O_Donoghue is asking a very interesting metaphysical question:
Christianity is based on the idea that if you believe Jesus was literally raised from the Dead …
then your sinful nature is redeemed, and you will be resurrected at the end of days (or, at the least, will be consciously enjoying an afterlife while waiting for the End of Days).
Islam, which invests quite a bit of the Quran on the history and life of Jesus and his mother, recognizes Jesus as a great prophet, but sees resurrection of the afterlife as not requiring a belief that Jesus was resurrected.
Mormonism, which is a form of Universalism, teaches that all humanity will go to one of three possible Heavens. Thus there is no requirement to actually believe in a resurrected Christ to accomplish the desired end.
And before there was Jesus, there was a form of messianic-style of Judaism that believed in the sanctification of humans (think transfiguration) without any martyr required to make it happen.
No doubt there are some who think it rather odd that the metaphysical machinery of the cosmos can only work if a person believes in a particular legendary event - - which might be likened to the idea that a nuclear reaction can only happen if enough humans believe in the existence of electrons.
Zoroastrians also believed in a resurrected afterlife … without requiring anyone to believe in the resurrection of any particular individual.
Perhaps the oldest of all resurrection cults is the original Egyptian cult of Osiris! Pharaoh, and any aspiring Egyptian who could afford some sort of bodily preparation, thought an eternal afterlife was the natural result of being tested by the pantheon of Gods that defended Maat:
"The earliest surviving records indicating that Maat is the norm for nature and society, in this world and the next, were recorded during the Old Kingdom, the earliest substantial surviving examples being found in the Pyramid Texts of Unas (ca. 2375 BCE and 2345 BCE). Later, as a goddess in other traditions of the Egyptian pantheon, where most goddesses were paired with a male aspect, her masculine counterpart was Thoth, as their attributes are similar. "