It's not hard to Google "violence in the new testament"
Look. you want me to tell you all the problems with these? Because there are a lot of problems with context and misinterpretation. I'll spend the time, just ask. Thats a lot to cover though, so I'll PM you the details unless you want me to adress something specific here.
However, I will address the main argument. The main gripe these writers, and presumably yourself, have is that God will eventually bring ruin to his enemies in violent ways, and that Jesus condones the actions of the old testament as the representative of the new covenant.
First off, Jesus is both the son of God and the incarnation of God. God is the same God at any point in time. Of course he would agree with himself.
Second, God is the definition of true Justice by christian standards. It is his job to judge and punish the guity and to defend and aquit the innocent. There is the key.
You see, the big difference between Christianity and Islam is that the Muslims are called to judge those who sin, whereas Christians acknoledge(or SHOULD acknowledge) that only God can truly judge what is right, and that Vengance is the Lord's.(see deuteronomy 32:35 and Romans 12:19).
Christians are actually advised not to take revenge and justice into their own hands. That is why any terrorist group commiting violent acts in the name of the Hebrew God is most certainly not of the Bible or of God.
If God truly cannot stand one of his enemies any longer, he will deal with it. Not us.