A random thought I just had, possibly insanely implausible...
Now, many Christian missionaries from Judea and Syria spread the religion out to places like Greece and Italy... it seems to me a major reason for this was because all these areas were united under the Roman Empire. Along the way, Christianity absorbed many Roman elements, and the largest Christian church is still based in Rome. Now, Syria and Judea were often disputed areas, and it seems to me possible that they could have fallen into the hands of the Parthians had Rome been weaker for whatever reason, for example a longer-lasting Hellenstic state in Asia Minor and Cilicia (to break a land connection) or something. Now, I think that Jesus could have still ended up crucified whether Herod Antipas is a vassal of Rome or Ctesiphon. What kind of Christianity would develop in Parthia?
Now, many Christian missionaries from Judea and Syria spread the religion out to places like Greece and Italy... it seems to me a major reason for this was because all these areas were united under the Roman Empire. Along the way, Christianity absorbed many Roman elements, and the largest Christian church is still based in Rome. Now, Syria and Judea were often disputed areas, and it seems to me possible that they could have fallen into the hands of the Parthians had Rome been weaker for whatever reason, for example a longer-lasting Hellenstic state in Asia Minor and Cilicia (to break a land connection) or something. Now, I think that Jesus could have still ended up crucified whether Herod Antipas is a vassal of Rome or Ctesiphon. What kind of Christianity would develop in Parthia?