1. III. Truth Will Not Associate With Deception (7-11)
    1. C. Dealing With Deceivers (10-11)

Matthew Henry

10-11
Deceivers must not be treated as though true ministers of Christ, who will Himself distinguish them one from the other. However generous we may be in providing for true ministers of Christ, we must take care that that generosity not be shown to one who works the destruction of souls. From their endeavors, we must be certain to withdraw our prayers of support as well (not that He'd be inclined to answer such prayers, anyway.) Such blessings of prayer certainly belong to the true evangelist, but not to such a one as this. What we may not be able to prevent, we ought at least not to support. We must take especial care to avoid partaking of other peoples' sins, for there are any number of ways we may share in their guilt: silence, lack of concern, private or open contribution to their waywardness, etc.
 
 

Adam Clarke

10
Let nobody preach under your roof that doesn't preach true doctrine. They should not even be wished the blessings of health or peace. Such blessings, according to custom, are reserved for those of like religion - the peace understood by the Hebrew encompassing every spiritual and physical blessing. The statement is essentially to "have no religious connection with him" nor to act in such a way that others might think you consider such a one as a brother.
11
The command is to remain separate from their teaching, neither to accept them as Gospel ministers, nor to attend their meetings. This is not a complete anathema, such a one still deserves such charity, mercy, and prayer as we would have for any non-believer. We are not to persecute them, as such judgements remain the sole province of God.
 
 

Barnes

10
As one accustomed to providing for visiting teachers, the lady stands in all the more need of being warned not to do so for those whose teachings are false, especially as regards Christ's doctrine regarding Himself and His religion. We are not told to restrain from all acts of kindness, but to treat them as we would any other neighbor. We are, however, to avoid anything that would seem to lend credence to their erroneous teachings. (Pr 19:27 - for to listen to them would be to stray from knowledge and discipline.) We should not treat them as teachers, nor recommend them to others, nor give them any reason to use our name as a commendation for their errors. Neither wish them joy, or health, or otherwise salute them, for such would be seen as wishing success to their teaching. (Mt 26:49 - Such a greeting was given Jesus by Judas at His betrayal. Ac 15:23 - and to the Gentile Church by that at Jerusalem. Ac 23:26 - and between the Roman leaders. Jas 1:1 - and by James to the Church.) While we are to love all people, and desire their welfare, we cannot and ought not to wish them success in their sin, but rather pray for their correction.
11
To give any sign of approval for their deception is to share in their sin. (1Ti 5:22 - Even the laying on of hands can bring a sharing of sin, if it is incorrectly applied.)
 
 

Wycliffe

10-11
In fact, such false teachers were being accepted into the homes of Christians, thus the requirement for a corrective warning. The warning is to stop this custom of acceptance, and actually enjoins a removal of all Christian hospitality. Such charity would make a person one who fellowships with the deceiver, and a joint worker with antichrist. And so, a seemingly godly act would become in truth an act of evil.
 
 

Jamieson, Fausset & Brown

10
Such deceivers will come - in the guise of a teacher or a brother. True love will separate itself from all falsehood, for misbelief destroys the very faith on which love is founded. This strong rejection is reserved for those who claim Christianity, yet subvert the doctrines of Christianity. The greeting rejected is not the general greeting of formality, but the loving greeting given to a fellow believer in recognition of brotherhood.
11
To greet a deceiver thus would be to wish him well in his opposition to Christ, and to have communion with his evil deeds. One cannot commune with both Christ and Antichrist. (Lk 9:54 - Whereas John's fiery nature used to get out of line, here it is properly directed.) Defense against heresy is right and proper.
 
 

New Thoughts

It remains a difficult call, as to whether we are to shun them completely - deny them all charity, or if the restriction is less severe. If it is truly a complete cutting off of such a one, I can understand the need. For as was noted, to do otherwise would be to aid and abet an enemy of the cross. But then, what does Scripture say to do for one's enemies? Hmm. I think that perhaps in this there is an answer? On the other hand, if we are to remain charitable but not supportive, the line becomes very difficult to discern. Where is the balance, Lord? I concur with the note that Mr. Clarke puts forth regarding persecuting of such a one. Vengeance is Yours, is it not? Although, I suppose there's room for exception where You require a particular person to act in a particular case. I'm not sure that I can justify the idea of complete and utter removal of charity to them. You did not utterly remove Your charity from them, did You? How then, should we? Neither did You remove Your charity from us when we were of the enemy's camp, but rather, You wooed us to Yourself by that very charity. God help us, to keep from becoming judgmental in the face of error. And I thank You, by the way, that You have heard my prayers and come swiftly to my aid! You're awesome, God. Thanks.