You could be in the middle of radical Islam (or other un-Christian) central, and you still wouldn't be in the right to attack Muslims unless it was for defense.
Given that you're Australian, there's a higher chance that you are Roman Catholic (which would explain your earlier comment). In the Bible, there is a clear case that can be used as analogous to this situation. Christians in the Roman Empire were being persecuted by the Romans. Some Christians contemplated uprising. Instead, they were exhorted to not uprise--the Roman government was the one sanctioned by God. All governments rule because God lets them rule.
Christians aren't supposed to respond to injustices tit for tat.
Bible verse link.
Also, vengeance is God's. Christians shouldn't comport themselves in a vindictive behavior (obviously Christians are fallible).
Pigeon pucks, JMP. Christ wasn't averse to violence, in defense of what's right. Matter of fact, He had quite a temper.