Sin is what fills the Gap between you and God in heaven. Adam and Eve were the first to sin ( to disobey God / rebellion/ turning your heart away from God)
There is the sin we are born with in our blood from adam and eve..that makes it so we have death ( that is why we die because of sin) Before Adam and eve sinned they did not die , the continauly lived. Also people in the begingng lived hundreds of years opposed to 70 to 100. But us dying is actually God showing us mercy, because it is sooo hard being sperated from God for so long.
We also sin against God in our hearts and bodies. ( fornication for example)
look at Galatians 5 in your bible. We sin in our hearts...when we accept Jesus as our savior The holy spirit comes in us and dwells with us and purifies our hearts. So even if you lived a seemingly good life, it still isnt enough to go to heaven without Jesus.
Jesus Died on the cross to bridge the Gap between us and God. He took all of the sin and the wages of sin on Himself and died in pain and agony. God even had to turn away from His son whom He loved because the Sin that was brought on him on that hour at the cross. Because Jesus Died, we are able to repent of our lives. In the old testament, people would slain sheep and so forth for a sacrifice to cover their sins, That is why Jesus is called the Lamb of God. Jesus made is so we did not have to have an innocent animal slain and We could go to heaven now.
When you confess Jesus as your lord with your heart and mouth, you are saved..you have accpeted that Jesus died for your sins personally. So now you are able to comune with God and your sin is not in the way. Now when you have Jesus as your savior, but you still sin...it depends. We will always be sinners. It is in our blood...Yet God purifies our hearts and minds, but our bodies are still of this world and they are dying and selfish. So it can be a battle...easily won if you life in the power of the holy spirit. As a christian you will sin everyday.. sins like...( being selfish, not loving, not forgiving someone, being hateful, hurting someones feelings, lying) You confess those sins daily and God works with you to change your heart so that you slowly do them less and less. Other sins that lead to death are sins like Galatiions 5:
But if you are led by the Spirit, you are not under the law.
Gal 5:19 Now the works of the flesh are evident, which are: adultery, fornication, uncleanness, lewdness,
Gal 5:20 idolatry, sorcery, hatred, contentions, jealousies, outbursts of wrath, selfish ambitions, dissensions, heresies,
Gal 5:21 envy, murders, drunkenness, revelries, and the like; of which I tell you beforehand, just as I also told you in time past, that those who practice such things will not inherit the kingdom of God.
Gal 5:22 But the fruit of the Spirit is love, joy, peace, longsuffering, kindness, goodness, faithfulness,
Gal 5:23 gentleness, self-control. Against such there is no law.
Gal 5:24 And those who are Christ's have crucified the flesh with its passions and desires.
Sins like that list, if you do them all the time and do not repent...well you will build a wall between you and God and you will grieve the Holy spirit who is sealed inside of you...and well God says that fornicators and such will not enter the kingdom of God.
So its all up to us. God gave us a way with his son Jesus to have a pure relationship with him, or we can not accept Jesus as our savior and ..well not go to heaven or have a relationship with Him. When your sin is not in the way with you and God..the bible says He will hear your prayers and answer them according to his liking and for your best..you will have his protection and guidence, and you will be able to understand the bible. People cant understand the bible unless they are saved, because it is the spirit of God that teaches us the bible. ( I personally know this one is true) ...
and the bible grows us closer to God as we read it and meditate on His wisdom, which we dont have acess to outside of God.
I hope that answers your questions!
e-mail me if you want.
oh and after you become saved, which I hope you are/ or will..read your bible, because the whole gospel of matthew answers all these questions.