As a means of defence against raiding enemy armies, the OT cities were surrounded by fortified walls with massive wooden gates to prevent or control entry and exit (Josh 6:1; 2 Chr 14:7; Neh 1:3). The gates were considered a weak point in a city’s defence system, as it depended on the diligence of the watchmen and gatekeepers to allow entry only for the legitimate travelers, hence they had to be constantly alert to guard and monitor all those who passed through the gates, for if they were lax in their duty, everyone within the security of the walls were in jeopardy (1 Chr 9:24; Neh 7:1,3; Jn 10:3).
Gates must be continuously monitored
at the strategic entry points (be they gates, doors or highways to areas, facilities and especially our homes), commanding evil forces not to enter while permitting what is good and of God freedom of access to bless and transform, for just as we securely lock the gates when evil prowls we should open them wide to the good and beneficial.
It is my responsibility to enter by the right way
the narrow gate that leads to life. The wide gate that most people pass through leads to destruction” (Mt 7:13,14). While we are saved only by the grace of God rather than our efforts, we are to repent and meet the necessary requirements to enter (Lk 13:24; Rom 10:9,10; Eph 2:8,9). Entering through the narrow gate that leads to heaven is difficult because of the resistance of our human pride, our natural love for sin, and the opposition of Satan and the world's values, all of which battle against us in the pursuit of eternity in heaven.
Along with city gates, the temple gates and doors were important, admitting worshippers to meet with God. The Psalmist stated, “Open for me the gates of righteousness; I will enter and give thanks to the Lord…” (Ps 24:7,9, 118:19-21). "Enter His gates with thanksgiving and His courts with praise..." is a directive to not come empty-handed to the Lord, but bring an offering to Him who has done so much for us (Ps 100:4).
The popular expression, about entering 'the pearly gates' of heaven, actually describes the gates of the New Jerusalem, which is not exactly synonymous with heaven (Rev 21:1,2,21). While these gates will always be open, only those who are true believers can enter through them (Rev 21:22-27).