I read a book over the weekend by C.S. Lewis titled "The Great Divorce." It is written in the style of a novella and is thoughts on Heaven and Hell. The story is masterfully done (Lewis always is, in my experience), with the reader able to clearly pick out key arguments about the existence of a Heaven or Hell, as well as why people end up in one or the other.
One thing stuck out for me as I read the story, and has stayed in my mind since. In the story, there are many characters, each of which has their own hangup about something with the afterlife. Some are upset that a certain individual made it into Heaven. Others are frightened. Others attempt to seduce those in Heaven. Some are unwilling to forgive past transgressions. What struck me was, though each character had their own reason for being wary of Heaven, all were tied by a single thread: inability to put God (or anyone) before themselves.
After I finished the book, I pondered on it for a long time. The idea that people condemn themselves to Hell because they are incapable of accepting that something is more important than them is a very powerful one. Take a look at the so-called "seven deadly sins":
Lust - "I want that person for my own gratification";
Gluttony - "I don't have to control myself. I can consume whatever I want";
Greed - "I want more";
Sloth - "I don't have to work, others will do it";
Wrath - "How dare you! I am right!";
Envy - "I want what you have";
Pride - "I am more important"
If we go into Christian doctrine, time and time again, we see that we must abandon the self in order to recognize that God must come first. When Jesus is asked what is the greatest commandment, his response is the core of the faith: "Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment. And the second is like it: 'Love your neighbor as yourself.' All the Law and the Prophets hang on these two commandments" (Matthew 22:37-40 NIV). Browse through the Ten Commandments, and you will find the same sentiments. Go to 1 Corinthians 13:4-7, the "Love Chapter" in the Bible and you'll see it there too. We are told to love our enemies and to forgive those who sin against us, because in doing so, we are letting go of our pride and anger and whatever else. Forgiveness, therefore, is a willingness to put aside our selfishness to gain something greater.
While the story points out in the beginning and again at the end that one should not take its view of Heaven and Hell literally, I believe that the points it makes are still valid for determining how one would attain Heaven. Essentially, our lives here are to gain experiences and build ourselves. Once we die, we do not gather more experiences, so we must rely on what we know. If all we know of in our lives is selfishness, then we cannot enter Heaven, because we don't know how to love God above ourselves. However, if in this life we can learn how to remove ourselves from the position of ultimate authority, and instead trust God, we are already preparing ourselves for eternal life.
Note that, if this observation is true, Christians are not given a free pass. We, too, must continually be reminded that we are not to live selfish lives. Becoming Christian is not enough, you must live it. Proclaiming that Jesus is Lord is not enough, you must follow Him.