The New Testament was originally written in Greek. It was translated in approximately 400 AD by Jerome into what is now known as the Latin Vulgate Bible. Understanding history and the original intent of the authors of the scriptures is so important to understanding clearly their perspective which can help inform and align ours so we can come to know Christ more clearly.
Jesus would have had to have been a master of many languages during his mortal life. There are many stories of his travels to Egypt, England, and possibly India that do not reside in our current King James Bible. He definitely spoke Greek, the main language spoken for business across the world at that time. He likely also spoke Aramaic (a dialect of Hebrew), Egyptian, Latin, Gaelic, and possibly other languages – but most everyday language, even in Palestine, was Greek.
This is important to understand because most of the modern world has taken the Catholic meaning of the word “repentance” and applied it to almost every modern day Christian religion (i.e. protestant, evangelical, and even modern Mormonism). In classical, or Koine, Greek the word that keeps getting translated into English as “repentance” is the Greek word: metanoia.
It is a conjugation of two Greek words “meta” and “noia”. Most modern day English speakers are familiar with the prefix “meta” in words like metamorphosis, metastasize, etc. meaning “change” but most are unfamiliar with the suffix “noia”. Noia in Koine Greek was the most internal part of a person – their truest self. We sometimes refer to this in modern English as “mind” or “heart” when trying to describe our innermost selves. So the earliest Christians would have clearly understood that when someone spoke and said “metanoia” it did not carry the same connotation that most modern Christians (after 400 AD) took repentance to mean. To them, it literally meant to “change one’s heart/mind about someone or something”.
Jerome took this word (metanoia), keeping in mind this is after 4 centuries of Christians gaining popularity and taking over (in some cases very ruthlessly) and imposing a certain prescribed dogma of belief (think: Council of Nicea), and was under instruction to make the Latin translation conform with the current beliefs/doctrines of the Roman Catholic Church.
Remember, by about this time, the Church was focused on controlling people’s behavior and beliefs and requiring certain acts of punishment or payment to the authorities to remove the sin of the individual. Jerome took the Latin word “paenitentia” which came to mean “penitence” or “penance” or acts of penance that had to be done if one hoped to obtain salvation (via the Church) or grace. Repentance has literally come to mean, in our modern venacular, to "punish yourself over and over again."
There is another word that is super-important to understand the concept of repentance here from the earliest Christian mindset – without imposing the rigid Catholic, Protestant, or sometimes even Mormon concept – that is the word “sin”.
In the Greek New Testament, the word translated “sin” by the Catholics and King James translators is “hamartia”. It literally (and originally) had to do with a marksman firing an arrow. In classical Greek, the word meant “bad shot, missing the mark, error”. Aristotle took that word and applied it to mean something like a “flaw in character” which could ultimately lead to a person’s downfall. So at the time of earliest Christians they likely understood the original meaning, but also its application towards behavior.
The reason I feel like it is so important to understand these words and their original meaning is that 1) context matters, 2) when divorced from understanding the original meaning all sorts of authoritarian abuse can take place, 3) we should not take modern meaning from words and misapply them – you can create all kinds of spiritual abuse internally – an overburden of guilt, shame, self-loathing etc. All that just because you made a mistake, you missed the mark, you erred. Stop it.
To properly metanoia (change your heart/mind) you have to understand how you hamartia (missed the mark), then you can work with Christ on changing your heart/mind to let go of that character flaw. He’s not standing over any one of us, as sometimes we have misbelieved, waiting to "kick our asses" if we mess up. Think of Paul, think of Alma and the sons of Mosiah. It is much simpler than that. We just need to recognize where we have erred and change our minds. Let go over the overburden of guilt, shame, and punishing yourself over and over again - that is of the Accuser (Satan) not the God of Heaven.