Pastors can have a tendency to expect attacks to come on the church from the outside. But Paul warns the Ephesian elders that wolves are going to attack the church from within.
Acts 20:29 – I know that after my departure fierce wolves will come in among you, not sparing the flock; 30 and from among your own selves will arise men speaking twisted things, to draw away the disciples after them.
Excerpt taken from, “What Are the Pastors’ Roles in the Church?“
Guarding the church against wolves is not fun. It's very hard. But we are to follow the example of Jesus Christ to lay down our lives, to lay down our comfort, to lay down our reputations, and defend the church from wolves. I was sharing with Mack and Tim earlier today, when I was thinking of the Lord's calling in pastoral ministry, I thought about the responsibility to protect the church, but I always had in my mind that this protecting of the church would be from outside coming in. I thought, yes, we'll protect against heresy from coming in. We'll protect against the cults from trying to break in. We'll be protecting the church from all that's trying to get into the church, but if you paid attention to what Paul said here, he said "fierce wolves will come in among you, not sparing the flock, and from your own selves will arise men speaking twisted things to draw disciples away after them. Therefore, be alert." Yes, pastors, we must equip our people and protect them from outside assaults of the enemy in untruth and heresy. But I would say even more pointedly, you must protect the church from wolves within infiltrating the assembly, teaching twisted things - sometimes outright heresy and sometimes by magnifying something else above Jesus Christ and the Gospel as the centrality of the church. Again, I think I could bring every pastor in this room up and they could give example after example after example of having to deal with this in the local church. I'll tell you that these wolves typically come into the church very passionate people, speaking a lot openly with seeming joy about the Word of God. They're often very vocal. And another characteristic of them is they're often very likeable. And the reason why is they draw people unto themselves. But it's not too long before they begin to teach twisted things to the sheep. And I want to exhort myself and all the pastors here: be on the alert. You guard the flock from within.