'Door' in the Bible

Truly I say to you, He who does not go through the door into the place where the sheep are kept, but gets in by some other way, is a thief and an outlaw.

He who goes in by the door is the keeper of the sheep.

So Jesus said again, Truly I say to you, I am the door of the sheep.

I am the door: if any man goes in through me he will have salvation, and will go in and go out, and will get food.

But Peter was kept outside at the door. Then this other disciple, who was a friend of the high priest, came out and had a word with the girl who kept the door, and took Peter in.

Then the girl who was the door-keeper said to Peter, Are you not one of this man's disciples? In answer he said, I am not.