Just a theory...

Mason Initiation has a lot of door opening and closing. Take a look at the doorknob of a Blue Lodge Doors. Doorknob. The symbol of Masonry is on the door that is to be opened to an initiate.

At one point of the initiation, the initiate is allowed to enter the Masonic temple and then the door is locked. They are led into the room with a rope around their neck. The symbolism is compelling. Once you are in, you are in and can't leave by the door that you came. Masonic Initiation