There is a way to absolutely prove that the word repent means to change ones mind in the New Testament when it is used in passages that tell us how to be saved.
1. We know for certain that the word for repent in the New Testament is the Greek word Metanoia (the verb for repent) or Metanoeo (the noun for repentance)
2. We know that during Jesus time, many Jews could not read Hebrew but they could read Greek, and so they read a Greek translation of the Hebrew Old Testament called the Septuagint.
3. We know that the Jewish Scholars in Israel who translated the Hebrew Old Testament into the Greek Septuagint chose to use the Greek word Metanoia in all 13 times where the Old Testament says that God changed His mind about something.
4. Therefore we know that, to the Jews who lived over 2000 years ago, the Greek word for repent (metanoia) meant to change your mind rather than to turn from your sins. (although it CAN mean to change your mind about sin if the context calls for that interpretation) God presents Himself as changing His mind about something but never presents Himself as turning from sin.
5. Examples: Jeremiah 18:9-10 God is speaking and He says And at what instant I shall speak concerning a nation, and concerning a kingdom, to build and to plant it; If it do evil in my sight, that it obey not my voice, then I will repent of the good, wherewith I said I would benefit them. KJV
Here in this Old Testament verse, the Greek word for repent is Metanoia. The Jewish scholars chose the Greek word Metanoia to say that if the nation did evil then God would repent or change His mind regarding the good that He was planning to do for the benefit of that kingdom. The passage is not saying that God turned from His sins. The passage is saying that God will change His mind about doing good things for a nation if they do evil. So Metanoia means to change your mind about something. (although, as I said, it can mean to change your mind about sin if the context of the verse demands that interpretation)
Amos 7:3 Here in this passage God says that He will send locusts swarms over the land and cause famine. Amos prays that he wont do it. So God repented (changed His mind) and assured Amos that it wouldnt happen. Again the Greek word the Septuagint uses is metanoia. So the word metanoia cannot mean to turn from sin. It means to change ones mind.
Now it is true that God repenting (changing His mind) is an Anthropomorphism. God doesnt actually change His mind but only speaks in the manner of humans to get an idea across. But the point is still the same .namely God represents Himself as changing His mind about a certain matter. He does not turn from sin. So the New Testament Greek word for repentance (metanoia) means to change ones mind about something and that is precisely why the Jewish Scholars who translated the Hebrew Old Testament into Greek chose the Greek word metanoia to say that God changed His mind.
6. Sometimes metanoia in the Septuagint simply means to study or know something so that you are sure of what you believe. Proverbs 14:15 says The simple believeth every word but the prudent man LOOKETH WELL to his going. Here we see that the Jews used the Greek word metanoia (repent)
for looketh well. So it means to think things through and decide what you believe about a thing. That is not really different from the meaning of changing ones mind because whether you change your mind or whether you think about a thing to know what you believe, either way it is simply rejecting that which is false and coming to believe the truth. This is exactly what the word metanoia (repent) means in the New Testament. Metanoia does not mean to turn from sins it means to change your mind so that you reject falsehood and believe the truth.
Now in passages in the New Testament where unbelievers are told to repent (metanoia) it means to change their minds about Christ and believe in Him. We are justified by faith alone and not by works.
Turning from sins is a work. Jonah 3:10 says that God saw their works, that they turned from their evil ways.
Works and turning from sin are the result of getting saved not the cause of getting saved.
ONE FINAL WORD the Old Testament word which often means (but not always) to turn back or away from sin is Shub. It is found 1,056 times in the Old Testament. Not one single time does the Septuagint translate Shub with the Greek word Metanoia! 13 times the Jewish Scholars used the Greek word metanoia to say that God changed His mind but not once did they use the word metanoia to mean that a person should Shub. (turn back from sin) So they obviously didnt believe that Metanoia meant Shub (to turn from sin.) They thought it meant to change ones mind. The Septuagint is what the Jews in Jesus day used. So what they meant by repent (metanoia) is to change your mind.
So Jesus and the Apostles would have used repent in the same way if they had any desire at all to communicate to the Jews in a way that they could understand.
1. We know for certain that the word for repent in the New Testament is the Greek word Metanoia (the verb for repent) or Metanoeo (the noun for repentance)
2. We know that during Jesus time, many Jews could not read Hebrew but they could read Greek, and so they read a Greek translation of the Hebrew Old Testament called the Septuagint.
3. We know that the Jewish Scholars in Israel who translated the Hebrew Old Testament into the Greek Septuagint chose to use the Greek word Metanoia in all 13 times where the Old Testament says that God changed His mind about something.
4. Therefore we know that, to the Jews who lived over 2000 years ago, the Greek word for repent (metanoia) meant to change your mind rather than to turn from your sins. (although it CAN mean to change your mind about sin if the context calls for that interpretation) God presents Himself as changing His mind about something but never presents Himself as turning from sin.
5. Examples: Jeremiah 18:9-10 God is speaking and He says And at what instant I shall speak concerning a nation, and concerning a kingdom, to build and to plant it; If it do evil in my sight, that it obey not my voice, then I will repent of the good, wherewith I said I would benefit them. KJV
Here in this Old Testament verse, the Greek word for repent is Metanoia. The Jewish scholars chose the Greek word Metanoia to say that if the nation did evil then God would repent or change His mind regarding the good that He was planning to do for the benefit of that kingdom. The passage is not saying that God turned from His sins. The passage is saying that God will change His mind about doing good things for a nation if they do evil. So Metanoia means to change your mind about something. (although, as I said, it can mean to change your mind about sin if the context of the verse demands that interpretation)
Amos 7:3 Here in this passage God says that He will send locusts swarms over the land and cause famine. Amos prays that he wont do it. So God repented (changed His mind) and assured Amos that it wouldnt happen. Again the Greek word the Septuagint uses is metanoia. So the word metanoia cannot mean to turn from sin. It means to change ones mind.
Now it is true that God repenting (changing His mind) is an Anthropomorphism. God doesnt actually change His mind but only speaks in the manner of humans to get an idea across. But the point is still the same .namely God represents Himself as changing His mind about a certain matter. He does not turn from sin. So the New Testament Greek word for repentance (metanoia) means to change ones mind about something and that is precisely why the Jewish Scholars who translated the Hebrew Old Testament into Greek chose the Greek word metanoia to say that God changed His mind.
6. Sometimes metanoia in the Septuagint simply means to study or know something so that you are sure of what you believe. Proverbs 14:15 says The simple believeth every word but the prudent man LOOKETH WELL to his going. Here we see that the Jews used the Greek word metanoia (repent)
for looketh well. So it means to think things through and decide what you believe about a thing. That is not really different from the meaning of changing ones mind because whether you change your mind or whether you think about a thing to know what you believe, either way it is simply rejecting that which is false and coming to believe the truth. This is exactly what the word metanoia (repent) means in the New Testament. Metanoia does not mean to turn from sins it means to change your mind so that you reject falsehood and believe the truth.
Now in passages in the New Testament where unbelievers are told to repent (metanoia) it means to change their minds about Christ and believe in Him. We are justified by faith alone and not by works.
Turning from sins is a work. Jonah 3:10 says that God saw their works, that they turned from their evil ways.
Works and turning from sin are the result of getting saved not the cause of getting saved.
ONE FINAL WORD the Old Testament word which often means (but not always) to turn back or away from sin is Shub. It is found 1,056 times in the Old Testament. Not one single time does the Septuagint translate Shub with the Greek word Metanoia! 13 times the Jewish Scholars used the Greek word metanoia to say that God changed His mind but not once did they use the word metanoia to mean that a person should Shub. (turn back from sin) So they obviously didnt believe that Metanoia meant Shub (to turn from sin.) They thought it meant to change ones mind. The Septuagint is what the Jews in Jesus day used. So what they meant by repent (metanoia) is to change your mind.
So Jesus and the Apostles would have used repent in the same way if they had any desire at all to communicate to the Jews in a way that they could understand.