But can we always have enough tolerance ? If in your country you had a community of people performing human sacrifices on unwilling victims, would you be able to tolerate it ? When something goes against our morality it may be very difficult to accept. The "usual" problem is religious belief, but it is necessarily the only one.

(If you think that the above example is a bit far fetched, consider that it is not much different from what some persons think about other people eating meat).