What makes a good person?

Yes it is about overcoming sin. No it is not impossible. We all at some point have become addicted to something or even someone, and it is damaging for us, and we have to overcome it. That is exactly what Christ Warned about when He Said that if you practice sin "you are a slave to sin (Gospel according to St. John, chapter 8, verse 34)."

Putting the threats of punishment in the afterlife, aside for minute, let's not forget that we do that in THIS LIFE. When people break the laws of their own land, they face legal troubles which may mean many years in prison (depending upon how serious the crime is). 

I was taught that living an evil life could lead to going to Hell for all eternity. I was also taught that I could go to prison (in this life) for being evil too.

Oh, I don't know about that. In prison, depending upon how serious the crime you committed, you may have to be put in solitary confinement, because the chances are you will have the snot beaten out of you by other inmates. Even being in solitary for a very long period of time can be mentally damaging. So either way, the person loses.

Rape is pretty prevalent in prison too. 

Back to the Christian afterlife: I am Catholic, & Catholics also teach that besides Heaven & Hell, there is also Purgatory, which is pretty much like jail in this life, in that it is for those souls that can repent in the afterlife and go to Heaven. I believe I read online somewhere, that Orthodox Christians actually pray for the souls in Hell, as they believe that it is possible to still be Saved after going to Hell.

Protestants are pretty much the only ones that have a really stark black & white  view of Heaven & Hell in the afterlife.

You are talking about inmates who are doing illegal things inside prison. 

The fact that Christianity is so broad and different sections have different beliefs is a major problem. All of them teach immoral things though. They also teach moral things. This makes sense considering all of this was likely just made up by human beings. 

Do you not believe the Christian God is the same God from the Old Testament? The God that murdered every human except for one family? The God that ordered entire groups of people to be slaughtered, even the children? The God that killed every first born in Exodus?

It is one thing if you see the Bible as metaphor, it is extremely harmful to see as literal. 

The Roman Catholic Church, the system that made up stuff to fill in the blanks of stuff that is still argued about among theists to this day because of how ambiguous much of the Bible is, is the same system that has been protecting child raping priests to save face.

Human Life is under the Will Of God, whether that life ends after only 2 days or well after a century.

The difference between one person killing another person and God Taking the life, is that the life still exists. God simply Separates the soul from the body.  Moreover, it is not just in the Bible that the Great Flood occurred. Practically all religions and cultures teach that there was a world wide flood, brought on to wipe out the wicket that took place in the world, and that the only people that survived were the ones whom God Deemed worthy to survive, & repopulate the world.

No, Purgatory is in Scripture. It is in the 2 Book of Maccabees (in the Catholic & Orthodox Old Testament, but, not Protestant Old Testaments), & it is is in St. Matthew chapter 12, verse 31.

I would say what makes a good person is someone who has faith in God, goes out of their way to help others, and seeks to bring out the best in people.

That is not "doing good", to go out of your way to help others, unless you know exactly what you're doing, and you're not hurting anyone else by helping others. 

The safest way to know you're doing good is to help an individual against a mob. Then you know you're not hurting anyone 99.9999% of the time. Or maybe just 99.9% of the time. 

Otherwise, going out of the way to help others is actually helping a mob to falsely persecute an individual who is an outsider. That is what happens 100% of the time in Louisville. That's just the way it is. For example, helping the gangsters and mobsters who prey upon the poor, what the demon possessed people call "giving someone a second chance" just makes them able to enhance their resources and skills to prey upon the poor even more. I've seen it work that way 100% of the time. 

And the people giving human monsters that "second chance" before letting any of their prey have a "first chance" know full well that their claims of "helping others" is a lie. They know they're Satanists in their spirit, because plenty of people tell them that the poor people deserve a first chance, and the people in gangs are never the "poor" people. They prey upon the "poor people". 

Let us take the sinners of 30 A.D. or thereabouts in Jerusalem, Nazareth, Canaan, the entire area. Jesus helped those who were individuals. Matthew was a tax collector who was ostracized. The woman being stoned was ostracized. They were individuals. Whatever gang they affiliated with, they were not accepted as actual members. The Romans didn't have banquets for Matthew. We know he wasn't a fully accepted member of Rome because we know that the Hebrews felt safe in ostracizing him. 

You can't say gang members or mobsters are ostracized. That's proven by the very fact that they get second, third, sixth, fifteenth chances before the actual poor people get a first chance. They're revered members of the community even before they decide to quit gangs. 

Yet it is easy for people to "help" the rich. Much easier than helping the actual poor. That's because gang members are accepted into gangs only because they have resources, riches, and skills. Gangs don't accept just anyone. You have to be skilled. Lock pickers are skilled locksmiths. Mechanics are skilled mechanics. Lookouts have 20-15 vision and super fast vision. Not a single gang member is needy. Any gang member can make a fortune in some legitimate field, and they know this. They're told this. Lookouts know they could make hundreds of thousands of dollars even if they only hit .222 in the major leagues. They know this.


So they're "easy" to help, which means that if we just look for someone easy to help, we locate those who don't need help. Jesus helped those who needed a lot of help. 

Let's not get technical.  
To the extent that there can be such a thing as "good" people, they cannot include atheists or agnostics (by your lights).