Why does freedom from sin or from Egypt require a separation of three days?
Three days signifies complete separation from captivity. Just as Israel needed three days to be separated from Egypt, salvation requires Christ's three days and three nights in the tomb to separate believers from the old life of sin and bondage. Without that gospel premise—death, burial three days, resurrection—there is no gospel.
Les teaches that Matthew 12 records the scribes and Pharisees asking for a sign, and Jesus answers that an evil and adulterous generation seeks a sign, but the only sign given is the prophet Jonah. As Jonah was three days and three nights in the whale's belly, so the Son of Man would be three days and three nights in the heart of the earth. Way back in Exodus, God was already giving a picture of basic premises: there is no setting us free from the shackles of sin any more than Israel could be set free of Egypt unless they had three days separating them from their place of captivity. It is the same in salvation. If we ignore the basic premise of the gospel—that Christ died, was in the grave three days and three nights, and rose from the dead—we have no gospel. But when we put our faith in that gospel, those three days and three nights in the tomb separate us from the old life of sin and bondage.