There is good and bad in everyone, though the proportion varies a lot from person to person. Just as a shepherd separates sheep from goats, or a farmer separates the wheat from the chaff, so Jesus will separate us on the basis of how we led our lives.
The problem is that everyone has a certain amount of bad in them - everyone is a sinner. Would it be a good idea for heaven to be home to any violent, spiteful, or criminal people? If we came across these traits in the next world, would it really be paradise, or would it simply be more of the same as we had on earth? Before going indoors on a wet day it is a good idea to take your muddy boots off and leave them by the door. On entering heaven, sins are left behind. It is Jesus, though, who decides who can come in. Believers, of course, are welcomed, but everyone else has to hope that their lifetime of a mixture of sins and good deeds somehow gets them in.
Those who do enter heaven are counted as "saved". Jesus promised that anyone who believed in Him during their lifetime would be saved. The act of being saved through faith in Christ is "salvation" and He is our Saviour. In this life if you do wrong you are liable to be judged by a court, sentenced and then serve the sentence. Afterwards your debt to society is paid off. How would you feel if a friend offered to take your punishment on your behalf on condition that you both remained friends?
A person who would voluntarily take someone else's punishment would "redeem" them from their crime and would be their "redeemer". Such people are few and far between. When Jesus allowed Himself to be whipped, to have a crown of thorns put on His head and then to be nailed to a wooden cross and left to die was symbolically taking the punishment for a lifetime of sins on behalf of anyone who believed that He was the Messiah, the son of God. By voluntarily taking our punishment He is our Redeemer and by therefore leaving us now sin-free we are saved and can enter heaven. Jesus is our Saviour.
Can you think of anyone you love enough that you would accept a death sentence on their behalf. That's how much Jesus loves you. Become a believer and accept His love. Don't reject Him after what He did for you.