Can an atheist go to heaven? The question of who goes to heaven and who to hell seems to result in very different answers depending on which tradition the Christian answering belongs to. Some traditions, especially evangelical Christians, seem to hold belief in God/Jesus to be the only important factor, while other christians seem to also put value on the actions one has done in life. 

The most common answer I heard (from liberal Christians) is that we can't know for sure who goes to heaven and who to hell, and that hell hopefully is even empty. 

What are the official positions of the major traditions on whether only faith can prevent one from going to hell, or if the deeds you perform in life might also get you into heaven, even if you don't believe in the Christian God?
This question is actually pretty cut and dry. At the core the main thing you ask is "Can I go to heaven even rejecting Christian belief by substituting some set of actions?"

No. No amount of works of any kind will get you into heaven. There is no substitute for faith.


  Hebrews 11:6 (ESV)
  And without faith it is impossible to please him, for whoever would draw near to God must believe that he exists and that he rewards those who seek him.


In fact it is not even necessary to split this up by different traditions inside Christianity. All of us pretty much agree on this point. The disagreements about works only come in when you discuss whether you need some works IN ADDITION TO faith or whether it is possible to have faith but no works at all. Mainstream Christianity doesn't believe you can get into heaven if you reject faith.

In fact, still speaking for the majority of Christianity and not just my tradition, I can say that this faith also has to be in Jesus.


  John 14:6 (ESV)
  Jesus said to him, “I am the way, and the truth, and the life. No one comes to the Father except through me.


The question about works should be asked in another question. Whether some kind of works are a requirement in addition to faith is the source of much debate in Christian circles. Yes some traditions "put value on them" that others do not, but those views have no bearing on your question because at the core none of those different views allow you to substitute faith with anything, only perhaps supplement (or legitimize) it. Since they are not relevant to the main question I will refrain from inserting them here. Also, questions about exactly what faith in Jesus needs to look like will turn up many variations. Save those for other questions. Also not in scope here is what happens to people who haven't heard or have heard and believed miss-information.