Sin: Sin at the door—“Sin lieth at the door” (Genesis 4:7).
Substitution: Blood on the door—“Take of the blood, and strike it on the two side posts and on the upper door post of the houses” (Ex. 12:7).
Salvation: Passing over the door—“The Lord will pass over the door” (Exodus 12:23).
Security: Preserved behind the door—“The door of the ark … the Lord shut him in” (Genesis 6:16;7:16).
Sanctification: Nailed to the door—“Bring him to the door” (Exodus 21:6).
Sentry: Sentinel at the door—“Keep the door of my lips” (Psalm 141:3).
Station: Looking for the Lord—“Waiting at the posts of My doors” (Proverbs 8:34).
—From 500 Bible Readings by F.E. Marsh.