THE GATES WILL NOT PREVAIL
Jesus said: "Upon this rock (of Peter's testimony that Jesus was the Christ, the Son of the Living God) I will build my church, and the gates of Hades shall not prevail against it" Matthew 16:18
Now the odd thing about Jesus' statement was this: Gates don't attack. Gates swing on hinges. About the only way a gate is going to hurt you is if you get your finger stuck in one - when it closes.
So, if the gates of hell aren't attacking us, what does it mean for Jesus to say "...the gates of Hades will not overcome/prevail against (the church)?"
It means: one of the reasons Jesus created the church was to attack the gates of Hell. He intended the church to take the fight to the enemy. We (the church) are the tool that He intends to use to take the Satan down, to tear his strongholds apart.
The church is a training ground for war -- but not a war like the ones we're fighting in Iraq and Afghanistan or other hot spots around the globe.
Paul writes: "The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds. We demolish arguments and every pretension that sets itself up against the knowledge of God, and we take captive every thought to make it obedient to Christ." II Corinthians 10:4-5