Now you just don't understand what heaven is, according to the Christian faith.
Heaven is a perfect place. EVERYTHING in it must be perfect. If it wasn't, it wouldn't be heaven anymore. It's like saying a cheese ball has to have cheese. If it didn't have cheese, it wouldn't be a cheese ball anymore.
God created man perfect, according to the Bible. As a stipulation of this, he gave man kind the *ability* to fail. Why? Because the ability to fail is pretty much the definition of free choice. Adam choose wrong, and listened to Eve and the serpent.
This made man imperfect.
So now we have a place where EVERYTHING must be perfect, and man, who is imperfect. Man and heaven aren't compatible now.
However, God has it in his heart to forgive your sins and make you perfect again. But he can't do that if you don't open your heart to him. He wishes he could, even wants to. But he just can't. He wants you to open your heart to him so he can forgive you and then so you can go to heaven.
Therefore, believe and you are forgiven and can go to heaven.
Don't believe and you stay incompatible with heaven, so you have to go somewhere else. ie, Hell.
God does not decide who goes and who doesn't go to heaven. If he had it his way, everyone would. But it doesn't work like that. Harvard wishes everyone was smart enough to get into it; it would make more money and be much happier. But if it admitted everyone, well, it wouldn't be Harvard anymore.
/logicked by Religion
Well, God can open your heart for you, to say he can't would disprove God, as God is omnipotent, and if he can't do something then he is not God. He just chooses not to, free will and all. But that's just nitpicking.
And that's one of the main reasons I don't believe in God or a Heaven. If heaven is so perfect, then I must have missed something because then how did Lucifer come about? Lucifer doesn't seem too close to perfection in my mind.
If the deciding factor between going to heaven or hell (and it is) is believing in God, then until I get concrete proof, non of this faith stuff, that he even exists, I have no reason to. I'd rather live my life happy and believe what I want than to believe a something that is most likely wrong, even if it turns out to be right in the end, than to force myself to believe a certain thing or way. There are tons of religions on this world, and each of them claims they are the right religion. Someone is bound to be wrong, though I actually hope that what I truely believe in is true:
That the human consciousness is a type of soul, and what it believes will happen most to it when it must leave the physical body, does. That is to say, every reilgion is right, and depending on which one you believe in, you get the end result of it. If you believe in Christ and lived a bad live, yoru soul will go to hell, yet if you believe that God doesn't exist and you cease to exist when you die, then that will also happen.
For me, the thought of living forever in a perfect place is a horrible thought. Living forever is a horrible thought in general. Even if you are blessed with eternal bliss and can never be sad, never be depressed, you still can never cease to exist. I guess for me, ceasing to exist is the final sleep. Where we can finally rest for an eternity.
You just keep proving my points for me. Thanks 
.
The Christian religion defines God as perfect. He has never made a mistake.
Therefore, he can be in heaven with his host of angels (who are also perfect).
Now humans on the other hand aren't perfect due to the sin we all carry. No amount of good deeds will ever erase this sin, so you will never be able to go into heaven. Unless God forgives you.
Analogy:
I really want to give you a thousand dollars. For free. For no charge, no strings attached. I'm just going to mail it to your house. This is God. He wants to free you of your sin and let you into heaven. You would owe him nothing, and it costs you nothing.
Now, to give you this money, I keep emailing you. And keep trying. And trying. But you don't believe me and think it's all just another scam. But I keep trying, and I never stop trying. All I want is to give you something free. All I need is your address so I can mail it. But you never answer me, thinking by giving me your address you'll suddenly get scammed everything. And that's natural; there ARE a lot of scammers out there.
This is what God is trying to do. He wants to give you amnesty and rid you of sin, and he never stops giving you chances to do so. He never stops trying to get you to believe. But you, the non believer, shut him out and refuse to listen to him, thinking it's all a lie. He can't prove to you he's real; he just tells you you have to believe. But you don't since you're very skeptic and think it is a lie (a very real possibility; there ARE lots of lies out there).
You just lost a thousand dollars. ie You just lost your chance at heaven.
No offense, but that is a horrible analogy. If God was in my inbox, well then, that's sort of proof he exists and I can believe in him. Or something similar. God isn't trying to get in contact with me. Having man write a book and then thousands of years letter claiming it's God's word is like playing the Operator game. Where one person says a phrase into someone elses ear and then say that phrase to the next person over and over and over again until you get to the end. In the game, you get to find out what the original phrase was, but with the Bible, you can't go back and find out what it original was to see if everything said was correct or how far off from the original it was. That's like you telling a random stranger to come tell me that you want to give me $1000. Why would, or why should, I believe this random person, when You could have easily came over and told me yourself?
And if heaven and his angels are so perfect, what about Lucifer? Or when the Angels came down and began having sexy time with the humans? Doesn't sound to perfect to me.
