What does Revelation 21:25 mean?

The gates of New Jerusalem will never be shut to those who qualify by faith in Christ to enter the city. In ancient times cities closed their gates at night to keep out hostile forces, but no hostile forces exist to threaten New Jerusalem. All kinds of evil occurred under the cloak of darkness in ancient times, as well as today, and hostile forces usually chose nighttime to invade an ancient city, but night does not exist inside New Jerusalem. The city's all-pervasive light emanates from the glory of God and the Lamb.

The perpetually open gates are a clear reminder that Jesus is the Door to heaven and He does not withdraw His invitation to enter (John 10:7–9). However, if a person rejects the invitation and dies, it is too late to change his eternal destination. Hebrews 9:27 states: "It is appointed for man to die once, and after that comes judgment." Second Corinthians 6:2 and Hebrews 3:15 offer valuable counsel: "Behold, now is the favorable time; behold, now is the day of salvation." "Today, if you hear his voice, do not harden your hearts."