The promise of heaven is one of the most powerful and motivating beliefs in human history.
In a survey by ABC News, nearly nine out of 10 Americans said they believed heaven existed.
But what exactly do people envision when they think of an afterlife, and what do they believe is required to get there?
Is heaven a myth dreamed up to give our lives meaning? Or is it a real place?
Barbara Walters traveled to India, Israel, and throughout the United States, talking to religious leaders of every major faith, believers and nonbelievers, scientists, celebrities … and even terrorists, in search of a better understanding of just what people believe when it comes to the afterlife.
Every culture has wrestled with the question of an afterlife, and most have come to a similar conclusion: The bad end up in hell, the good go to heaven.
If you were a Viking who died in battle, fierce goddess warriors known as the Valkyries would carry you to Viking Heaven, Valhalla, where you would join an eternal feast. The Romans thought they became immortal and were spirited off to Paradise on a fiery four-horse chariot.
The early Christians and Jews believed that man was not pure enough to enter the Kingdom of Heaven as flesh and blood. They believed all people were transformed into spiritual beings, filling Heaven with angels.
That belief has changed over the centuries, but angels still have an important connection with heaven. In cities all over the world, angels can be seen in watchful poses.
"We believe that they are the ones who take care of us. They are the messengers of God. They are the ones who are God's very special friends and his servants," says Cardinal Theodore McCarrick, former archbishop of Washington, D.C.
"I always think of heaven as being a place where we won't have any troubles anymore. Heaven is a place where there will be peace and tranquility," McCarrick says. As a Catholic, McCarrick believes heaven is more than a spiritual place. Catholics, he explained, believe the body is resurrected. "I'm looking forward to meeting my mom and dad and the rest of my family," he adds.
The Rev. Dr. Calvin Butts, pastor of New York's famed Abyssinian Baptist Church, tells Walters he has had many visions of heaven over the years. He describes heaven as "no tears, no mourning, no suffering. It's eternal joy and happiness because you are at one with God."
Butts is certain of heaven's existence, but says it's in an indescribable dimension. "Heaven is in another dimension. So you don't necessarily have to look up but you can look out and see heaven. Heaven is a fourth dimension if you will."
Walters traveled to India where she met with the Dalai Lama, considered by Buddhists to be the reincarnated Buddha. The Dalai Lama says that the purpose of life is to be happy, and that you can accomplish that by "warm-heartedness." He tells Walters heaven "is [the] best place to further develop the spiritual practice … for Buddhists the final goal is not just to reach there, but to become Buddha. [It's] not the end."
As a Buddhist, he believes in reincarnation and that people can have second lives as animals. "If someone do[es] very bad, badly … kill or steal … [he] could be born in an animal body."
Walters also talks to actor Richard Gere, a longtime follower of Buddhism. "I don't think necessarily heaven and hell happen in some other life. I think it's right now," Gere says.