It is all about space. And one door is a portal to the other. Man walks into a space and designates lots and puts up walls that then confine the existing space into smaller units and claims it as his own. He has a door or several others to have free access to the newfound space. It becomes his new home now. Then he allocates several rooms. This is how he goes about defining space into smaller units for each of his uses. He creates an altar that becomes a space for the divine energies to reside in. This goes the same for places of worship too. We have high walls that define the boundaries. We have several walls at times. We allocate space for each deity to reside.
Ramalinga Adigal in traveling the mystic bridge to the kingdom of God literally describes the structures he sees and the deities residing there. Each of them has a space to reside. As he passes them they come to acknowledge and greet him. Watching the Puranic movies we see the Gods walking through huge arches. These define their entry into another Logam or world.
Now after Agathiyar's bronze statue left for Sri Krishna's home, the door to Agathiyar's space is closed except when someone wants to walk in and meditate. This was what Agathiyar instructed.