@Sam I Am phil,
To answer that we have to get into the real causes of suicide bombing and crusading. Neither have religious causes.
Suicide bombing seems to come from the hopelessness of living in certain conditions, and sometimes from the hopelessness of seeing others, like family, live under certain conditions - like abject poverty, totalitarian brutality, the careless eradication of community tradition by self-interested outsiders, ect.
Crusading seems to have come from the extreme greed and materialism of medieval Europeans, along with a general disregard for the value of other people, and from the need of Popes (at the time, the greatest hedonists around!), for the sake of maintaining their power structure by diverting the jingoism of monarchs from one another onto an outside party.