Paul, apparently not a sailor, recognized how important it was for everyone to stay in the ship and eat.  If they did not, they would die.  For Reformation, it is important to emphasize that we stay in the ship, the church.  If we don’t, it will be fatal spiritually.  Here we have the refuge of Christ himself, who saved us from sin and death. Here we have the nourishment we need in Word and Sacrament.