The trouble is, we don't use apocalyptic literature in the way Paul's hearers were used to, so we hear it in a vacuum that they wouldn't have. To imagine how the recipients of Paul's letter would have heard apocalyptic material, we have to do a fair bit of work on getting familiar with the nature of the literature and the theology of time and the eschatological expectations of their world. This may sound like the sort of sophistication you are justly suspicious of, but I am not saying it applies so intensely to the whole Bible. I am suggesting that apocalyptic literature is a special case, and that's why we frequently have so much trouble with the book of Revelation. We need to expect similar problems when we run into the apocalyptic passages in the gospels and the epistles.

In a nutshell, I think that if it were addressing the specific passage (2Thess 1:5-10) it would say that although the apocalyptic language is full of violent sounding images, it does not say that the means God employs in defeating evil and avenging the righteous are actually violent. Apocalyptic literature portrays the struggle between the culture of God and the culture of death as a violent struggle, but as is seen repeatedly in the book of Revelation, it keeps subverting its own imagery by saying that the victory is won with "the word of testimony" and the "blood of the lamb". We are very used to thinking that "inflicting vengeance" must mean "killing enemies", but does it? Jesus inflicts vengeance by unmasking (shaming) the brutality of the powers and dominions and rendering them powerless over the life of the saved.

Peace and hope,

Nathan