There have been many debates held, and entire books written on the subject.

The official Catholic position, IIRC, is that in addition to heaven and hell, there is a waiting area (purgatory) in which souls of people who lived before Jesus were kept. Between Jesus's death and resurrection, he visited and preached to them in purgatory. Those who believed were saved and went to heaven; those who rejected him were sent to hell. Purgatory and Jesus' descent are not in the Bible, of course, and the theory is a bit convenient, but it does have a certain fairmindedness.

Calvinists, on the other hand, believe that everyone is condemned to hell from birth because of original sin. Unless someone has accepted Jesus, they are toast. Moreover, Calvinists believe in predestination, so they also believe that God selects certain people for heaven via irresistible grace, and there's pretty much nothing anyone else can do. In a legal or pedantic sense, all of the individual points are based on parts of the Bible. But overall, it offends peoples' sense of fairness and free will, and Calvinism is practiced in only a few parts of the Protestant world now, such as the Dutch Reformed and Orthodox Presbyterian churches.

Mainstream evangelical churches, of which the Baptist denominations are the largest, are a mixed bag. There is a widespread belief that infants who die go to heaven, but this is belief is held less out of any statements in the Bible and more out of moral rejection of the alternatives. Opinions differ on whether adults who die, never having heard of Jesus, go to heaven, hell, or are judged individually by God.

Michael Wood, who wrote "The Hidden Bible" and "Breaking the Romans Code," self-published books which sometimes appears in internet ads on DU, has some interesting observations. He believes that the phrase ‘aionios', translated as 'eternal' in English bibles, really means long-lasting but finite. So hell is a temporary punishment for sins committed in this life. He also discusses a passage in one of Paul's letters which he argues persuasively that Paul thought all of creation would eventually be reconciled to God. This is a minority view, but it can be argued seriously from the documents.

Personally, I think most of the authors of the Bible didn't really have this question uppermost in their minds when it was written. That's what oppression and a survival instinct will do to you. There were friends and enemies, and the enemies were against not only you, but your God, and were therefore evil. The weaknesses to this approach became obvious as the world became larger, more stable, and more secular. But unless something is crystal clear in the Bible, it's bound to result different opinions.