Its talking about the devil using people.
Here is the verse.
""""So it is no wonder that Satan's servants (ministers, preachers, teachers) also disguise themselves as ministers of righteousness".
In other words, they teach a form of godliness that is works based, that is not based on The Cross of Christ as the Devil's idea of "righteousness".
It will be...>"here is what you have to do"....> "you must do this.... "you must keep this"...
Its simply self effort in place of God's Grace, is what is being taught and the LIE is that they say, "its Salvation".
I agree that Satan poses, at times, as a minister of truth. For the trained eye, his "truth" is nothing but corrupted facts, or "untruths." The fact Satan can speak "truth" doesn't mean it is untrue. It is the fact his "truth" is not completely true makes it a "half truth," which is no better than a lie, or perhaps even worse, because it can fool people.
Let's apply this to fruit. If Satan "appears" to do something good, to help man with knowledge in some way, does that mean it is "true good?" Of course not! It isn't so much "fake fruit" but "fake good." So here we're probably talking about the same thing.
So when someone says, "You need to do this to be saved, you need to do good works to have Eternal Life," then this is an example of "fake good," or "fake truth." It appears to be someone wanting to get you Saved. And it appears someone wanting you to do good.
But the point is, it isn't really "good" that they're trying to get you to do. They may legitimately recommend doing some good, but in the context of Salvation, we know that doing good alone doesn't get anybody saved.
It is, rather, choosing to follow Christ that gets us saved. And that includes choosing to participate in Christ's righteousness, produced out of a new nature that we receive when we choose to follow Christ.
In choosing to follow Christ we choose, by default, to give up our own ways, our own independent living. We choose to follow Christ all the time, to follow the path of righteousness consistently. This is indicative of our choice to obtain a new nature, modelled after Christ.
I can't quote it enough times in this discussion.
1 John 2.3 We know that we have come to know him if we keep his commands. 4 Whoever says, “I know him,” but does not do what he commands is a liar, and the truth is not in that person. 5 But if anyone obeys his word, love for God is truly made complete in them. This is how we know we are in him: 6 Whoever claims to live in him must live as Jesus did.
Is this an effort to get saved by works? Of course not! It is the choice to follow both Christ and his righteousness. It is the *same thing!*
Some quote the common Protestant maxim, "good works doesn't save." But mouthing a common saying is not treating all of the intricacies of what choosing Salvation requires. Salvation is not negligent of choosing good, because in choosing Christ we choose a new nature, to embrace the good and to reject the evil, or self-centered approach to life.
To confuse good works with "fake fruit" confuses the issue. Unsaved people can do "good works." It just doesn't get them saved. It is not living the Saved life.
And so, we must distinguish "good works" from Salvation. But we must not render "good works" as "bad fruit" of necessity, simply because it is not from a Christian.
What makes authentic "good works" as "good fruit" is the fact that it comes from a Christian who has embraced a *new nature.* When something by nature does "good works" it indicates not just a brief display of good, but more, a good that reflects that it comes from something that is by nature good.
It is, as such, not a borrowed good, but an intrinsic good, arising from a good nature. That nature comes from Christ, when we choose to follow him. We not only do good, but we do good intrinsically, from a new nature.