Gates to a city stop the wrong people or animals from coming in, they also let the good people come in.
[Unit 7, BE 109, Transcript, 2]
"Zion is the daughter of God."
[ Unit 7, BE 109, Transcript, 3]
Psalm 87:4 says that Hebrews, Egyptians, Babylonians, Philitimes, Phoenicians, and Ethiopians come into Zion and they were true worshippers of God in Jerusalem.
[Unit 7, BE 109, Transcript, 4]
Psalm 87:4 also says "This one was born there."
"... the remarkable thing is that these people are Gentiles and that God is making them His own children and citizens of His holy city!"
"The issue is foreign born people born in Babylon and Egypt and Philistia and Tyre and Cush, foreign born people God is saying were born here. These people were born in foreign countries so what this psalm means is that these foreign nationals were born again. When they came to faith in God God viewed them as being born in Zion!"
[Unit 7, BE 109, Transcript, 5]
This relates to Nicodemus' questions to Jesus in John 3:3-