You need to read the the Bible more then. There have been quite a number of instances in reach killing people was considered a "good thing" and ordained by God. Hell, you can use the Bible to justify slavery and bigotry. Its all open to interpretation, but then again the Old and New Testament have been translated, retranslated, interpreted and reinterpreted for over 2000 years so there is no way to accurately to know what the original meaning of the scriptures meant.
Christians should emulate Jesus, not use the old testament as justification for killing people.
Christianity is both Old and New Testament, and then some depending on which faction you are with. There is more to Christianity than just emulating Jesus, Blank. Sad, but true.