‘Here I am! I stand at the door and knock. If anyone hears my voice and opens the door, I will come in and eat with that person, and they with me.’ (Revelation 3 vs 20)
You hear a knock at the door. Who is it? It’s Amazon making a delivery. It’s the postman leaving off a parcel. It’s someone calling to read your electric metre. Often, these days, when someone knocks at your front door they do so for functional reason. A quick ‘hello’, a quick signature, and they are away again.