And as it is appointed for men to die once, but after this the judgment. …
God told the first man, Adam, he could eat of any tree in the garden (including the tree of life, signifying eternal life). However, Adam was commanded not to eat of the tree of the knowledge of good and evil, signifying trying to choose for himself what was right and wrong. Even though Adam was allowed to choose whether he would obey, God made it clear that the tree of life was the right choice and that the consequence of the wrong choice was death (Genesis 2:16-17). As God told Adam and Eve after they made their wrong choice, “For dust you are, and to dust you shall return” (Genesis 3:19).
Adam brought the penalty of death on himself, and all mankind has made the same choice ever since. Human beings are mortal, and all will die once. Sin carries the penalty of death—not just physical death, but eternal death. But thankfully God planned for Jesus Christ to come and pay the penalty of death for those who will repent. His one-time death makes it possible for forgiven humans to not have to die the second death—eternal death.
The Bible teaches that after this physical life, humans will be raised to life—resurrected. Some will be judged forgiven and faithful and will enter God’s family in the first resurrection. Others will be raised in the Great White Throne Judgment. And some, hopefully few, incorrigible and unrepentant sinners will be raised to face the second death. These resurrections are explained in our article “Resurrections: What Are They?”