The questions we must first ask in relation to our question:
By what standard are people Good?
Does doing good negate doing bad?
Is it unjust for people who have done good to go to hell?
To classify good as good and evil as evil, there must be an objective standard of morality; otherwise, morals are subjective, making them relative to the person who determines them.
This would make murder no more right or wrong than inviting someone over for a meal. God has a strict standard of goodness that has been broken by everyone to some degree, whether that is by lying, lusting, or using His name in vain, for it is stated that the "wages of sin is death".
Just like we may pay a speeding fine to nullify the consequence of our speeding, we must also pay a fine to be forgiven of our sin. Just like a speeding fine, regardless of the good we have done elsewhere in our lives, for justice to be fair, we must pay the fine. Simply saying sorry is not enough to escape the fine.
Conclusion
Our sin, large or small, is charged to us by death. Our fine must be paid, and no amount of good deeds or apologies will be adequate for justice to be satisfied. Christ, however, has paid the fine for anyone who believes in him, as he has taken our punishment upon himself, just as someone else may take on the financial responsibility of paying your speeding fine if you accept their gracious offer.