There were a lot of people crying heresy and accusing Rob Bell of universalism. Those claims were based mostly off of the title and a book trailer. After actually reading the book, I believe that claims of Bell's flee from Orthodox Christianity have been greatly exaggerated.
So what does he say?
First, he plainly says that there is a heaven, a hell, a final judgment, a bodily resurrection and that there will be a new heaven and new earth. Is this Biblical? Yes. Second, he says that Jesus is the only one through which people receive salvation. Is this Biblical? Yes.
So far, so good.
He begins to stray from the pack in his discussion of who gets spend eternity with God and the permanency of hell.
He believes that because God is love, he would never be so exclusive as to make salvation dependent on human effort to spread the gospel. God works in ways that we don't know to save people who would never receive the gospel. It would be unloving for God to never give some people the chance to receive the grace that he so freely gives to all people if they will choose to follow.
Is this Biblical? Bell would say yes. I would say only God knows. God tells us to make disciples of all peoples and we should leave the rest up to God.
He also argues that the gates of New Jerusalem will not be shut and that there will still be opportunity for people to turn to Jesus after the final trumpet sounds
Is this Biblical? Sort of. The gates of New Jerusalem never shut, but I don't agree with Bell's interpretation. The verse says that the gates never shut because there is no night. My interpretation: God is in the city, he has banished the darkness (symbolic of evil) there is no more night (symbolic of evil), therefore there is no need to lock the gates, there is no need for security measures. New Jerusalem is safe because God has defeated evil once and for all.
So Heretic? Probably not. Stretching the interpretation of some scriptures? Yes. His interpretation, however, do not negate the saving power of Jesus and Jesus alone. Therefore, he's not a universalist either. If you need a label, he's an inclusivist. In his opinion there are people who will be saved (through Jesus) that we wouldn't expect.
Honestly, this is nothing new. There have been many Christians through the centuries to hold this. One of whom is C. S. Lewis. Although he never wrote a book specifically about this area of theology, one example is found in the Last Battle Lewis shows a Calormean entering Aslan's country who never followed Aslan. Aslan tells him that all the good he did for Tash, he actually did for Aslan. Another, although it's more like a parable than theology, is the story of the Great Divorce. A group of deceased ride a bus from Hell to Heaven and are given a chance to follow God even though they have already died and gone to Hell. These are both similar to Love Wins, but it should be remembered that these are both stories and not theological explanations.
Why did Bell write this book? Because he is so convicted by the fact that God is love, that he believes should show that love to all people. I think that most of us can get behind that. Christians should be known as a people of love because God is love. God loves people and in the end God's love rules the day. In other words, Love Wins.