Noah was shut in away from all the world by the hand of divine love. The door of God's electing purpose separates us from the world, which lies in the wicked one. We are not of the world even as our Lord Jesus was not of the world. Into the sin, the folly, the pursuits of the crowd we cannot enter; we cannot play in the streets of Vanity Fair with the children of darkness, for our heavenly Father has shut us in.
Noah was shut in with his God. "Come into the ark," was the Lord's invitation, by which He clearly showed that He Himself intended to dwell in the ark with Noah and his family. In this manner all the chosen live in God and God in them. Happy people to be enclosed in the same circle that contains God in the Trinity of His persons--Father, Son, and Spirit. Let us never be inattentive to that gracious call, "Come, my people, enter your chambers, and shut your doors behind you; hide yourselves for a little while until the fury has passed by."
Noah was so shut in that no evil could reach him. Floods simply lifted toward heaven, and winds helped him on his way. Outside the ark all was ruin, but inside all was rest and peace. Without Christ we perish, but in Christ Jesus there is perfect safety.
Noah was so shut in that he could not even desire to come out, and those who are in Christ Jesus are in Him forever. They are there forever because eternal faithfulness has shut them in, and infernal malice cannot drag them out. God closes, and no man opens; and when in the last days as Master of the house He shall rise and close the door, it will be futile for mere professors to knock and cry, "Lord, Lord open for us," for that same door which closes in the wise virgins will shut out the foolish forever. Lord, close me in by Your grace.