Zion was the high hill on which King David built a citadel, so it is often referred to as “the city of David” (2 Samuel 5:7). This explains why “Zion” is used as a symbol for the nation of Israel as well as Jerusalem, its capital.
Mount Zion was the name given to that hill section of Jerusalem that lay inside the city wall along the eastern side. A Canaanite fortress on the southern part of this hill had enabled the inhabitants of Jerusalem to withstand enemy attacks for centuries. When David conquered the city he determined to build a temple for God on Zion, though the site chosen was to the north rather than the south ( 2Sam. 5:6-9; 24:18-25; 2Chr. 3:1; Psa. 78:68-69; Isa. 8:18. The temple was built during the reign of David’s son, Solomon (1Ch_22:8-10).
Since the temple was God’s symbolic dwelling place, Israelites regarded Zion as a holy hill and Jerusalem as a holy city (Psa. 2:6; Psa. 9:11; Isa_52:1). They often used the name Zion figuratively to refer to both the temple and the city (2Kgs. 19:31; Psa. 9:14; 51:18; 87:1-3; Matt. 21:5). Because of the people’s wickedness and idolatry, Jerusalem, far from being a holy city, was a sinful city (Isa. 1:21; 10:11; Micah 3:10).
Nevertheless, Zion was the location of God’s symbolic dwelling place, and psalmists and prophets mentioned it repeatedly. To them it spoke of God and his salvation of Israel (Psa. 20:1-2; Psa. 53:6; Isa. 28:16; Micah 4:2; 4:7; cf. Rom. 11:26).
New Testament writers used Zion as a symbol of a far greater salvation, a salvation that is not limited to one city, one nation, one people or one era. To them it spoke of the heavenly Jerusalem, whose citizens are those ‘born from above’ (Heb. 12:22-24; Gal. 3:26-29; 4:26-28; Rev. 3:12; 21:1-4).