pulē

In the ancient world the gate was the most important opening a walled town had. It was the way in for traders, travelers, armies, and funeral processions, and it was heavy enough and guarded enough to decide who got through. That is what this word names, whether the wall belongs to a city, to the temple courts, or to a prison. It is a bigger and more public thing than the door of a house or room (θύρα), and it names the opening and its barrier rather than the gate building or covered passage you walk through (πυλών).

Because everyone and everything passed through it, the gate became a natural picture of a decision. Jesus tells his hearers to go in by the narrow gate, and the choice between the two gates is the choice between two roads and two destinations. Nothing about the picture is complicated: you cannot be on the road unless you have first gone through the gate that opens onto it.

The gate also stood for strength. A town's safety was measured by whether its gates held, so naming the gates of a place was a way of naming that place's might. When Jesus says the gates of the realm of the dead will not overpower the assembly he is building, the image is of death's fortress failing. The same habit of speech runs all through the Hebrew Scriptures, where the city gate (שַׁעַר) stands for the town itself and for the authority exercised there.

One last use is quietly loaded. To be outside the gate was to be outside the community and its protection, which is where refuse was dumped, where the dead were carried, and where executions were carried out. When Hebrews says that Jesus suffered outside the gate, the phrase carries all of that weight.