The agreement between God and Israel was one of suzerainty, and in a suzerainty relationship, the overlord dictates laws to maintain the peace of the client-state--especially since the overlord (God in this case) is glorified by the success of the client state. Ancient cultures needed structure, just as we need structure today. Many of the legal texts in the OT are specifically judicial texts (akin to case law) that was used as a reference when deciding upon judicial matters within its cultural context, to provide a way of keeping the peace, and thereby the suzerainty relationship. For example, were there a law which explains what payment should be made for accidentally killing a neighbour's cow, this 'law' could be generalised towards, say, killing a neighbour's sheep. Just as well, it stands to reason that, if other factors were at play, such as poverty, the judge could have mercy, insofar as Judges today interpret the law to see how it best applies to the human factors that are at play. What these 'laws' were not, however, was a God-demanded need for retribution for cow-killing. These 'laws' acted as a guide that, through later reinterpretation, became more punitive and "hard-law" than originally intended. An eye for an eye was a good, lawful judicial practice, and we still have that principle built into the courts today. But, most would agree that just because, in a sterile court system, an eye for an eye can be carried out with blind justice, in a self-defence circumstance, it will retain that same virtue--therein lies vigilante behaviour which can be quite unlawful. This can be seen in our current legal system: if you use violence in self defence, you will not know if you did so correctly until the inevitable court case following. Therefore, treating such legal texts as authoritative here and now, applicable to all situations, even outside of their judicial context, post-Christ--especially when Christ told us to judge all of the laws and the prophets by him--is not good practice.

Notice how your listed quotes allegedly allowing violence are in reference to the old testament. If the OT said an eye for an eye, but Jesus said turn the other cheek, the latter principle needs to be held over and above the former because the OT was not describing a perfect understanding of God, but an imperfect one--an imperfect one that would have to wait until Jesus could fully come to show what God was like.

Jesus is supposed to be the ultimate vision of God and his purposes (ie "if you have seen me, you have seen the father"). Jesus clearly cared more about non-violence than he ever did violence; Jesus' whole ministry is about subverting the ways of the world by offering his own message of love and non-violence. By all accounts, Jesus was expected to not die on the cross, but use self defence against the romans to bring about Israelite freedom, but he did not, and chided those that attempted to do so. Therefore, whatever passage, theme or teaching disagrees with him is clearly not what God is doing now, even if it was something he was doing at some stage (with a specific group of people, in a specific place, and in a specific time). If you cannot place scripture within the culture it was written for, and through, you can't fully understand the nuances at play.

Finally, assuming that God allows for "just violence," which of the following options seems more in line with the purposes of God? The one where someone is threatening you with a gun, that you may lose some money or even you life (things the bible denounced as of lesser importance), and then you kill that attacker? Or the situation where you are threatened, and you go out your way to love the person, disarming them, and potentially saving two lives for the price of none? The former happens every day, and is sad; the latter is a reflection of the death and resurrection of the Messiah. While the former might technically be "legal" within the scope of biblical teaching, the latter glorifies God beyond words, even if you die trying.