What does Psalm 118:20 mean?

The "gates of righteousness" (Psalm 118:19) belong to the Lord, and to Him alone. The temple was also referred to as "the house of the Lord" (1 Kings 6:1; 2 Kings 25:9; Jeremiah 7:2). This psalm may have celebrated the successful rebuilding of Jerusalem and its wall. Ezra describes the dedication of the temple (Ezra 6:16). Then, the people offered significant sacrifices to the Lord (Ezra 6:17).

In a literal sense, there were gates at the entrance to the temple. There, people could enter to formally offer sacrifices thanking God for His intervention. This passage also hints at the relationship between God and man, through Jesus Christ the Messiah. Jesus claimed to be the door to salvation (John 10:9) and that this was a single option compared to a broad path to death (Matthew 7:13–14).

Under the new covenant, there is no longer a single physical site for worship. Church buildings are not "the house of the Lord" in the way of the Old Testament temple (Acts 7:48). Rather, it is the believers in Christ—the people—who make up "the Church" (1 Corinthians 3:16; Ephesians 2:19; 1 Peter 2:4). This is why it is important for believers to gather together (Hebrews 10:25) and give the Lord thankful, joyful praise, in spirit and in truth (John 4:24).