What do you say when a non-Christian tells you that he doesn't believe that Jesus rose from the dead - that Jesus had a twin who came out from the tomb?
At first, theories like this "twin brother" theory seem creditable. There have been others that have proposed this theory, so your friend is not the first to make this assertion. For instance, Dr. R. Cavin of the University of California Irvine argues that Jesus had an unknown identical twin brother who began a hoax about the resurrection.*
Thankfully, there are scholars like Dr. William L. Craig. I would suggest you carefully listen to Dr. Craig's first presentation starting at the 8 minute mark. He does a masterful job attacking all the weaknesses and problems with this theory. who have refuted these theories. Listen to his debate here.
Here are my notes:
1. The "twin brother" theory cannot explain many aspects of the historical evidence for the resurrection including the supernatural appearance of Jesus (after the crucifixion) and the wounds/scars of Jesus.
2. Jesus was born in solitary in Bethlehem. For the "twin brother" theory to work, you must assume that Jesus either had a twin brother (there is no historical evidence for this) OR that the real Jesus was switched for a baby who had an identical twin brother. The problem with the 2nd scenario is that (1) there is no historical evidence that Jesus was "switched at birth" and (2) it is highly improbable (there weren't even other people around at the time, let alone another a crazy mother who decided to switch her babies with the real Jesus).
3. The "twin theory" assumes the twin brother is (1) a moron (Why would he want to "become" a person that the Jews want to kill as a heretic?) and (2) an unethical person (you'd have to be one in order to "trick" people into believing you were the resurrected Messiah).
4. Jewish tombs were sealed with a disc-shaped stone, which required several men to remove it. It is not possible that the "twin brother" could have taken out several elite Roman warriors and moved the massive stone all by himself.
5. The "twin brother" theory goes beyond what is known, i.e. it cannot explain all the other pieces of historic evidence for the resurrection. For instance, it cannot explain the eye-witness accounts, the radically changed lives of the disciples and the rise of the Christian church. Only the resurrection can. This is what Dr. Craig considers the weakest part of the "twin brother" theory.
Please note these are simply my notes. Dr. Craig's explanation includes more precise detail, so please LISTEN to the debate carefully. Dr. Craig does a great (and humorous) job in explaining why the "twin brother" theory is ridiculous. So friend, take heart. The resurrection of Jesus is a historical fact. The "twin brother" theory ... is just a theory.
[Answered by Pastor HM]
*R.G. Cavin in William Craig vs. Robert Greg Cavin. Dead or Alive? A Debate on the Resurrection of Jesus. (California: Simon Greenleaf University, 1995).