In any area of study specialists develop technical terms for the purpose of expressing specific ideas. In Christianity, terms like “substitutionary atonement”, “hypostatic union”, “trinity”, or “kenosis” serve an important purpose in explaining concepts related to Christianity. Having technical terms is not unique to Christianity. What is somewhat unique, however, is that the belief system is based entirely on ancient documents that were originally written in other languages. There is a long history about the translation of the Bible from the original Hebrew, Aramaic and Greek languages into English. Along the way, English translations have picked up their own terms that are used not like the technical language cited above to convey precise meanings, but for the sake of tradition. The words are almost entirely ones that you would only find in an English translation of the Bible and really they seem to have no precise meaning outside of their usage within the Bible and even the meaning there is a bit hazy. One such word is “repent”. It is not uncommon to hear Gospel presentations end with a call for the hearers to “repent of their sins” in order to be forgiven. I think most people have a vague idea of what it means to “repent” but if this act (ie repentance) is a key component of how one receives salvation, it seems there needs to be more than just a vague understanding. The first thing you will see from a Google search of the term is this definition: “feel or express sincere regret or remorse about one’s wrongdoing or sin”. Google’s definition follows closely the etymology of the word: it came to us via a Latin term that means to “make sorry”. This is a common way people understand the term.
Another definition of “repent” is the following:
Many understand the term repentance to mean “a turning from sin.” Regretting sin and turning from it is related to repentance, but it is not the precise meaning of the word. In the Bible, the word repent means “to change one’s mind.” The Bible also tells us that true repentance will result in a change of actions (Luke 3:8–14; Acts 3:19). In summarizing his ministry, Paul declares, “I preached that they should repent and turn to God and demonstrate their repentance by their deeds” (Acts 26:20). The full biblical definition of repentance is a change of mind that results in a change of action. (https://www.gotquestions.org/repentance.html)
The problem with this clarification of the term is that if to repent means to have a change of mind that results in a change of action, then why are the commands to both repent and to bear fruit in keeping with repentance (Luke 3:8; Acts 26:20)? If by definition when I am repenting I am changing my mind and I’m proving my change of mind by my actions, then there would be no need to have a separate command for the latter action. You don’t tell someone to, for example, stand up and to put all of their weight on their feet in an upright position.
The most common word translated into “repent” is the Greek word metanoeo. The main definition is “to change one’s mind”. Blue Letter Bible does provide an elaboration of this definition that includes the more emotion related terms of having contrition, to amend with abhorrence, etc. I think these additions are mainly theologically developed terms that aren’t precisely related to how they are used in the Bible. For example in the Thayer’s definition provided at the link above, it cites Jonah 3:9 as an example where repentance means “to feel sorry that one has done this or that”. “Who can tell if God will turn and repent and turn away from his fierce anger that we perish not” [KJV]. Here, the Septuagint authors translated the Hebrew term nacham into the Greek metanoeo. Nacham does carry with it the idea of being sorry, but it also connotes “having compassion” and “comforting oneself”. So of the three ideas: sorrow, compassion, comfort, what makes the most sense in Jonah 3:9? God was sorry for wanting to judge a sinful city, God was comforting Himself regarding a sinful city, or God was moved to pity/had compassion on a sinful city so turned from the disaster He had planned for it? Clearly this last idea fits best. Now if we carry this idea into the New Testament, is Jesus telling His listeners to “Have compassion” to “Be sorry” to “Comfort one’s self”, “for the kingdom of heaven is at hand” or is it possible that these three ideas from the Hebrew term nacham don’t precisely fit the context in which Jesus was using them. Instead, it makes more sense to take the base definition of metanoeo and hear Jesus as proclaiming, “Change your mind! For the kingdom of heaven is at hand” (Mat. 4:17). “…that they should change their mind and turn to God, performing deeds in keeping with their change of mind” (Acts 26:20).
If it is accurate that metanoeo primarily relates to a change of mind, then the next question is “change one’s mind about what?” This is answered by the Gospel of John, the book about belief that never uses the term metanoeo. The issue in regards to salvation is Jesus Christ: Who He is, what He did and whether or not one “believes this”! Unbelievers think the wrong thing about Jesus; they must change their mind and believe the right thing about Him! What should go along with this change of mind is a change of action, but the change of mind comes first! Telling people to repent comes with too much baggage; the issue is not the right amount of sorrow of particular sins, but the recognition that the sin problem has been taken care of by the person and work of the Son of God, Jesus Christ. Change your mind about Him and put your trust in Him!