The short and easy answer is “because the Bible says so.” The personal reason I believe Heaven exists is because humans were created with a soul which makes humans eternal. God’s original plan was to live among us and to live in perfect peace. Jesus paid this price so God’s original plan can be executed. Jesus’s death and resurrection is proof of Heaven. He declared, “I am the resurrection and the life. Anyone who believes in me will live, even after dying” (John 11:25). We are made heirs in God’s Kingdom because of what Jesus did for us.