John 12:24 NASB

Unless a grain of wheat fall into the earth and dies, it remains alone, but if it dies, it bear much fruit. Jesus is speaking of His own death here. Later, He says that if He is lifted up, He will draw all men to Himself (John 12:32). But He was also speaking of our death. Persecuted believers have plenty of opportunities to put this into practice. John 12:24 is why the church grows when Christians are martyred. Based on Colossians 1:24, persecuted Christians believe that they must die in order for people to be saved. They are right, I'm sure. When Jesus calls us, He invites us to die, both to self, and to physical death for the sake of the Gospel.