For God so loved the world that He gave His only Son that whoever believes in Him will not perish but have eternal life. John 3.16
Isn't it interesting that, according to this verse, everything - life and death and all that goes with them - everything hangs on believing. Some have a hard time with this because so much hangs on so little. And yet, this misses an important point. The separation of the world into two groups is not about those who believe on the one side and those who don't on the other. Everyone believes. The question is whom or what does a person believe. It is impossible to live without believing. A person's beliefs are simply the collection of notions that he has about how life works. So, different people believe different things: eating deals with hunger, the brakes in your car will slow you down, life works better if one is courteous, life works better if you think of yourself first, a good job will require a college degree, real living is impossible without Jesus. So, the verse is not really about whether we believe or not. It's about what we decide to believe about how life works best. And once we decide what we believe then we have believed in those things. We believe in those car brakes so we speed along the interstate at what would otherwise be insane speeds. We trust them to stop us when we want to stop. We believe in Jesus.
The verse is about believing truth according to the Bible and, therefore, putting your trust for now and for later in Jesus. Life and death and all that goes with them hang in the balance.