That part of the Bible always bugged me.
So, several accounts on the gospels accounts that crucified Jesus says, in Aramean, "Eli, Eli, lema sabachthani?" ("My God, my God, why have you forsaken me?").
Matthew adds that the people watching misunderstand him, and think he is calling the prophet Elijah, and make fun of him for this.
Why on earth would this happen? Since Jesus always was preaching in Aramean, I thought everybody spoke that language... Wasn't it the case?
I think you're overthinking things. Jesus had been badly beaten, was being crucified, was outdoors in front of a crowd of people who were yelling things and talking among themselves, and was literally dying at the moment when he uttered those words. I mishear things my wife says to me when she's standing 10 feet away in our kitchen.
I don't think it's all that hard to imagine onlookers confusing "Eli" (as in Matthew 27:46) or "Eloi" (as in Mark 15:34) with "Elijah." At this point, Jesus would have been on the crucifix for 3-6 hours. His words were probably neither clearly spoken nor clearly heard; think of how after a hard workout it can sound like you're adding "ah" at the end of every word as you catch your breath.
Anyways, a few explanations have been offered. One is an honest misunderstanding (as explained above). Another is wilful cruelty by purposefully misinterpreting Jesus' cry and maliciously mocking him. A third is that those present would've understood Jesus to be referring to the entirety of Psalm 22 (from which the quote comes), and thus expressing confidence in salvation.
Source:
https://books.google.com/books?id=hWkoFOvbWW4C&pg=PA421&lpg=PA421#v=onepage&q&f=false
There is an awful lot of speculation about those words, including the theory that jesus exclaimed this as the holy spirit left his body. Might be a better question for a theologian.
I'm sure theres a better subreddit for this question. Maybe a religious one? I don't know if the bible is considered factual around these parts.
I tend to agree with /u/sumpdiddlyump_ . However it's also significant that it is Elijah that they think he calls for. Elijah was expected to return to announce the end times (return rather than be resurrected, as the OT says that he was taken up to heaven rather than dying). John the Baptist was associated with this idea, but was now dead, having been killed by Herod Antipas.
Quite what this signifies, I'm not sure. For instance the crowd might be saying something like "They thought John was Elijah, but he's dead - and so will you be".