The New Testament is actually in Greek, if you go to any church in Greece they are reading from it in the original language and people understand it fine.
It certainly sounds strange and unlike how any modern Greek person would speak, but it can be basically understood especially if you are a bit used to it. I’m not an expert but I think it’s probably a smaller gap than say Latin and modern Italian. Definitely a smaller gap than English and Old English, despite being more than twice as old!
Even the Christian era of the Bible being distributed in Latin made perfect sense since it was originally mostly being distributed to people who spoke Latin with questionable accents (and where Latin was the language everyone who was literate was literate in).