I will make mention of Rahab and Babylon to them that know me: behold Philistia, and Tyre, with Ethiopia; this man was born there.
I was a bit confused when I first read this verse in Psalm 87. We all know Rahab was a person, not a country! But it's obvious that verse 4 is speaking of nations. So exactly what nation is Rahab?
Well, there are 2 other places in the Bible where Rahab is spoken of as a place instead of a person. They are Psalm 89:10 and Isaiah 51:9-10. The latter of these references makes it pretty clear that the reference is to Egypt (see the Red Sea crossing in verse Isaiah 59:10). Apparently the root word for Rahab means "boastful, proud, arrogant," which would line up pretty well with Egypt and its Pharaohs.
I did wonder whether there's any significance to the fact that the harlot of Joshua 2 and the nation of Psalm 87, Psalm 89, and Isaiah 51 share the same name, but I haven't come up with anything. Let me know if you have any thoughts.
Now, the entire Psalm focuses around verse 3, Glorious things are spoken of thee, O city of God. Selah. Zion, the city of God, Jerusalem – will one day be the center of this world's government, and commerce, and religion (Isaiah 2:2-5; Ezekiel 5:5; others).
The lesson for the boastful, proud, and arrogant nations of Egypt, Babylon, Philistia, Tyre and Ethiopia is that the only thing that was special about the lowly city of Zion is that God loved it, God chose it, God established it.
The lesson we need to remember when our hearts are lifted up in pride and arrogance and conceit is that the only thing we have going for us is that there is a God Who loves us, a God Who forgave us, a God Who has made us His children.
No particular reason He chose the city of Zion as the headquarters of His kingdom. No particular reason He chose to love us and send His Son to save our souls. But praise His name, He did!