Door is a closable entrance or opening. “The door thereof, when it was shut, was tight like unto a dish” (Ether 2:17).
A person praying is told to “enter into thy closet,” and, “when thou hast shut thy door, pray to thy Father who is in secret”. The Father “shall reward thee openly” (3 Nephi 13:6).
Someone said, “it is now even at your doors,” and directed others to search at the judgment-seat. The judge lay in his blood after being murdered by his brother, who sought the judgment-seat (Helaman 8:27).