You can see my post about of Islam.Maybe, It can help you to know about of our great religion. Please, don't blame anyone or any person for your lacking knowledge of this person or religion.
Allah Said in Holy Quran-
O you who have believed, let not a people ridicule [another] people; perhaps they may be better than them; nor let women ridicule [other] women; perhaps they may be better than them. And do not insult one another and do not call each other by [offensive] nicknames. Wretched is the name of disobedience after [one's] faith. And whoever does not repent - then it is those who are the wrongdoers.
So, try to think about of this religion.
History/man deeds cannot be an example.For that reason, you can't blame all of us.The main theme of Islam is "Peace".
You may have overseen something important regarding the interpretation of the Quran: The rule of abrogation.
What the rule of abrogation?