Christians have done the same.
When?
Are you equating Christians with Muslims who stone rape victims, who murder their daughters in “honor killings” and who keep girls from getting an education? You are certainly exhibiting a pernicious hatred for Christians that is totally unwarranted.
May as well say that criminals are justified in their behavior because police also sometimes commit crime. The former is behaving true to form and the latter against everything he or she has been taught and is supposed to stand for. One easy example: Christianity was ultimately responsible for the abolition of slavery, a human institution that existed in every culture back to the beginnings of recorded history. Under Islam it is justified by the Quran and is still quietly practiced. Did some Christians own slaves and even try to use the Bible as justification? Yes. Does that make it OK, no. Because Jesus taught against that and many other behaviors, some of which Muslims call justified based on Mohammed’s teaching and example. So please take that remark and put it somewhere dark and safe. It won’t work here.