Matthew 16:18, “… on this rock I will build My Church, and the gates of Hades (hell) shall not prevail against it.”
I just wanted to review the focus of this verse. First let’s ask what usually has gates? Simply put in context, a kingdom and its city would have gates. The Bible is full of references to people meeting, conversing or selling at the city gates. Think walls of Jericho. In this passage, the interesting thing to see, which sometimes gets missed, is that Hades (or hell) is said to have gates. Seems strange at first thought to ponder why they would want to keep someone out. I mean, walls and fences are for just that, keeping in those who are accepted, and to keep out those who are not. So now I’ll ask in typical Sunday school fashion, “who is Satan and his crew seeking to keep out?” Jesus! (The usual correct Sunday school answer to almost any question). The kingdom of Satan is in jeopardy now that the true King of kings has arrived. Jesus teaches this as He goes proclaiming that the reign (or translated “Kingdom”) of God is at hand. If the new reign of someone is beginning, then the reign of whoever preceded Him is over.
It is not the focus of the verse that the church is the one with walls struggling to withstand the assaults of Satan (True but taught elsewhere) but that the reign and kingdom of Christ cannot be stopped by any stronghold of Satan. In a type of kingdoms standoff, David was a prefiguring of Jesus when he stood against Goliath (1 Samuel 17). Two warriors fought a winner takes all bout. Jesus states that such a battle is already won when He teaches that He has bound the strong man (Satan) and are even now plunders his goods (Matthew 12, Mark 3). The church breaks forth into the world in the New Testament and no matter where it goes the great commission rings true that disciples are being made in all nations (book of Acts).