Your perspective on history is totally wrong. The crusades were a defensive measure to push Islam out of europe, and regain the Holy land from the muslims. Christians held the holy land hundreds of years before there every was a mohamid or islam.
Science owes much of it's history to the christian faith. Sir isac newtin, who many consider the greatest scientist of all time, was a devoted christian.
125, of the first 126 universities in america were christian [includding harvard,prinstan,and yale], and established to train christian ministers. It was christians who established most of the higher learning intitutions all over the world. [Darwin owes his education to Christians]
Christianity has had its problems, but not because of what we believe, but be cause of a departure from what we believe. The biggest perverter of the gospel, is evolution, and in that perversion has been the most deadly.
The printing press was invented to print bibles so the common man could have the scripture for themselves, and sparked the reformation, which took care of the strangle hold rome had on christiandom. the middle ages were not the times of the churches highest influence. The roman church is not the best example of christ. The influence of christ grew expodentually after the reformation, and as it grew, the influence of the church made every reagion it touched more prosperous, educated, and free.
You do not have the right to pervert history, simply because you hate Christ, and don't want to admit it is evolution that endangers humanity, while believers in Christ have laid down their lives to make things better for man kind.
Hitler most asuridly is an example of what pure, godless evolution produces, when goes unchecked. Secular humanist realized this, and rewrote the humanist manifesto, the doctrine of their religeon.'