Why do people blame the majority by the actions of a few?

Because the majority, who are not engaging in those acts, turn their backs, close their eyes and mouths. That majority in your first example was Christian, in your second Muslim.

Edmund Burke correctly said, "All that is required for evil to prevail is for good men to do nothing."

"For example, generalizing all christians by the actions of the crusade, and the inquisition, eventhough Christ said to put down the sword?".

I don't. However, many of the Christians who don't want to be judged on the basis of the Crusades and the Inquisition are anti-abortion rights zealots, creationists, anti-gay rights perverts and "this is a Christian Nation" traitors, and that gives me a perfectly fair basis on which to condemn them.

Just because they weren't involved in the Crusades doesn't mean that they can act however badly they want.

the crusades were undertaken by thousands of christians, and would have been impossible without the support of thousands more.

similarly suicide bombers need an entire society which is at least willing to go along with jihad before they can function properly.

during wwii the allied troops didn't attack only nazis who had personally offed jews. there is such a thing as a corporate responsibility.

It's human nature to stereotype people into groups

The apple doesnt fall far from the tree

With respect to Christianity only, I agree.

How about the largest genocide of them all,the flood.

Or shouldn't the christian god be judged by his actions in the bible

"Stand rigid for the next battle"

"Peace means reloading your guns"

"The love for life is all hatred in disguise"

Aren't you doing exactly the same thing?

People?Don't you mean "some" people.

they can't see the forrest for the trees?