Jesus rose from the dead. That is certainly the principal belief that propelled the spread of the Christian faith across the Roman Empire, inspiring thousands who persisted in that belief in the face of either a martyr’s death or loss of fortune or even family. Had these early Christians not believed in the resurrection of Jesus, it is almost certain that Christianity would not exist today, because it would never have existed at all.
So, why did the early disciples of Jesus Christ believe in His resurrection? Is the resurrection of Jesus historical? For further reading, here