"Behold, I stand at the door and knock; if any man hear My voice, and open the door, I will come in to him, and will sup with him, and he with Me."
(KJV) Revelation 3:20

"The closed door was the obstinately shut mind, the weeds the cumber of daily neglect, the accumulated hindrances of sloth"
Pre-Raphaelite Brotherhood, pg.350 - W Holman Hunt, 1905

The door in the painting has no handle,
and can therefore be opened only from the inside.

"Thy word is a lamp unto my feet, and a light unto my path."
(KJV) Psalm 119:105

And, Mistletoe symbolizes love.
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