Etymology does not dictate meaning. Repent means more than a change of opinion regarding facts. For that a different Greek word is available, and was used when the islanders changed their mind about whether Paul was a murderer or a god, after surviving snakebite.
Here's the Greek word from Acts 28:
metaballō
1) to turn around, to turn about
2) to turn one’s self about, or transform one’s self
3) to change one’s opinion
Repentance in Scripture is connected to a change in conduct; for instance when people responded to John the Baptist's call to repent, it was with, "what should we do?"
Here's the Greek word from Acts 2:
metanoeō
1) to change one’s mind, i.e. to repent
2) to change one’s mind for better, heartily to amend with abhorrence of one’s past sins
I believe your view is mistaken. In fact, you've gotten it backwards. Metaballo is about a change in direction or conduct. Metanoeo is about changing one's mind.
It seems you are saying all commands in the Bible, besides "Believe on Jesus Christ" are optional as far as salvation is concerned.
Quite a broad brush stroke, eh? By "optional", no other command involves getting saved, or staying saved. However, anything and everything we do has CONSEQUENCES. So no one gets away with anything.
That contradicts this passage in I Corinthians 6:
"Or do you not know that the unrighteous will not inherit the kingdom of God? Do not be deceived; neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor homosexuals,
10nor thieves, nor the covetous, nor drunkards, nor revilers, nor swindlers, will inherit the kingdom of God.
11Such were some of you; but you were washed, but you were sanctified, but you were justified in the name of the Lord Jesus Christ and in the Spirit of our God."
In the Greek, there is no article (the) before "unrighteous" in v.9 as there is in v.1 when Paul specifically mentions unbelievers. Also, to "not inherit the kingdom" carries the same meaning as a parallel passage in Eph 5:5 - For this you know with certainty, that no immoral or impure person or covetous man, who is an idolater,
has an inheritance in the kingdom of Christ and God.
So, to "not inherit the kingdom" and "has no inheritance in the kingdom" are parallel. iow, there will be no eternal rewards for such people.
This is not about not getting into the kingdom.
It really makes no sense why God would not save everyone, from your understanding of salvation. If it takes nothing but believing one proposition to be saved, why should it even take that?
These are silly questions. The Bible tells us that we must believe in Jesus Christ to be saved. That is God's plan for mankind. Ask Him if it doesn't suit or please your view.
Also, it makes it look like the thing we need to be saved from is not sin, but God's odd sense of justice; since the sin can remain unchecked in a person and they be saved, as long as God has someone to punish for it.
There is obvious misunderstanding or a lot of confusion about what Christ actually did on the cross from these statements. He PAID FOR ALL SIN. There are no sins He did not pay for. So sin cannot be the issue for any believer, or even any unbeliever. I've gone round and round with Calvinists on the fact that no one goes to hell for their sin. They go there because they never received God's gift of eternal life, and are therefore not qualified to live with Him in eternity. One must have God's life, which is eternal life, to live with Him in eternity.
Everyone else experiences the "second death" which is the lake of fire beause their names were not in the book of life.