THIS MIGHT SURPRISE YOU
The answer
Hebrew, Latin and Greek. John 19:20 says many people read the sign because the place was near the city, "and it was written in Hebrew, in Latin, and in Greek." Matthew, Mark and Luke give the wording of the sign, and their main text names no languages at all.
Why it’s interesting
A footnote at Luke 23:38 in the NRSVue translation says some ancient handwritten copies of Luke do add the languages. It lists them as Greek, Latin and Hebrew, the reverse of John's order. The New Oxford Annotated Bible, a study Bible, notes that in Luke the title King of the Jews was the central issue of Jesus's trial.
Scholarly consensus
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