An existential threat is defined as an event that could cause human extinction. Mr. Smith begins this Bible study by looking at some of the threats that most people worry about such as invasion from outer space, global warming, or a large asteroid striking the earth. The chance of any of these happening is extremely low, but in Matthew 24:21-22 the Bible does identify a threat that mankind will bring about that would end all life on this earth if God did not intervene and take over the rule of this world.