Regardless of the precise meaning of the metaphors, you can see that, in this passage, Jesus did not mention evil spirits. The closest He came was His mention of the “gates of Hades,” which are of course symbolic, as there is no way that the literal gates of Hades could do anything to hinder the church.
What do the “gates of Hades” represent? Perhaps they are symbolic of Satan’s power, and Jesus meant that Satan’s power would not stop His church from being built. Or, perhaps Jesus meant that the church He would build would save people from the fate of being imprisoned behind Hades’ gates.
Notice that Jesus actually made reference to two sets of gates: the gates of Hades, and the gates to heaven, implied by His giving Peter the “keys to heaven.” This contrast further supports that idea that Jesus’ statement about Hades’ gates is representative of the church’s role in saving people from going to Hades.
Even if Jesus did mean that “all the power of Satan would not stop His church,” we cannot jump to the conclusion that His comments about binding and loosing are instructions as to what we should be doing with evil spirits over cities, for the simple reason that we can find no examples in the Gospels or Acts of anyone binding evil spirits over cities, nor can we find any instructions in the epistles for doing such a thing. However we interpret Christ’s words about binding and loosing, our interpretation must be supported contextually within the rest of the New Testament.
In light of the absence of any scriptural example, it is amazing how often Christians say such things as, “I bind the devil in Jesus name,” or “I loose the angels over that person” and so on. You don’t find anyone saying such things anywhere in the New Testament. The emphasis in Acts and the epistles is not on speaking to the devil or binding and loosing evil spirits, but on preaching the gospel and praying to God. For example, when Paul was being continually buffeted by a messenger (literally, “angel”) of Satan, he didn’t try to “bind” it. He prayed to God about it (see 2 Cor. 12:7-10).
