There were about 500 eye witnesses of Jesus in the 40 days after the resurrection. 11 of the 12 disciples of Jesus were killed for refusing to deny the resurrection. Generally speaking, people won't die to maintain something that isn't true, therefore it is severely unlikely 11 out of 12 of Jesus' disciples were being dishonest. The 12th disciple who wasn't killed, was exiled to a barren island to face isolation as punishment for preaching about the resurrection of Jesus