Fall of Man
Christians generally believe that everyone who is related to Adam is born with sin and would never make it into Heaven. Jesus, who was related to Adam only through Jesus' mother, had no sin, and died to remove the sins of those who believe in him. They believe that whoever believed in Jesus Christ was given a "second chance" to get back into Heaven, shown in John the Apostle's Gospel: "...God loved the world so much that he gave his only Son, so that everyone who believes in him would not be lost but have eternal life." (John 3:16, ERV) Different types of Christianity have slightly different ways of viewing the fall and salvation through Jesus. You can see the different views below.