What if Jesus had been cremated?
Assuming here he'd been burned and returned to life:
If he'd been crucified and then the body burned to offend Jews, a symbol like the Methodist holy fire wrapped around a cross would be THE universal Christian standard, not a minor sect.
The Ash Wednesday ceremony would become the Easter standard. We'd have burning bowls a la Buddhism and burn reminders of our sins so that the ash can be scattered to the windows or buried in a garden to spring hope anew.
Far more of the New Testament stories would refer to holy fires, not holy lights. Baptized by water and by fire would have more emotional weight.
The Catholic church would have no complaints about cremation, since Jesus did it. Fast forward a millennia, and you wouldn't have nearly as many Christian churches built out of bones or the Parisian crypts.
Walking hot coals and passing through the fire would be kosher with Christianity (pun intended).
Christianity would have appropriated the Phoenix myth and used that instead of the butterfly as a symbol of transformation.
Would have made no difference as He was resurrected as a spirit being and materialized many different bodies when He appeared to His disciples after His death. We know this as many times the scriptures indicate that they did not recognize Him when He appeared to them.
Have you ever heard of the "Phoenix"? (Phoenix (mythology) - Wikipedia)
If a bird can do it, imagine God himself.