First, the very obvious … Jesus’ resurrection from the dead. If you notice, Jesus appeared to his disciples when they were gathered as a community. He wanted to make sure that he was seen by every one of his close followers. And every time Jesus appeared to his disciples after his resurrection, his disciples were initially terrified - that’s why he had to greet them, “Peace be with you”. Jesus wanted to reassure his disciples that there was no need to be afraid because it was He and not some ghostly projection. And to further supplement Jesus’ assertion, he even got a piece of baked fish and ate it in front of them to prove that it was Jesus, all flesh and bones.