Something I am curious about is what has shaped people's views on this issue.
In my case, it has been reading these publications:
Robert Fisk Pity the Nation, The Great War for Civilisation (am aware of the criticisms that have been made of him, by the way).
Martin Bunton The Palestinian-Israeli Conflict - A Very Short Introduction
As to what compels people to do terrible things to each other, Philip Zimbardo's The Lucifer Effect is very good on that. Also, from Jonathan Haidt's The Righteous Mind I learned that we are a tribalistic species who tend to make instantaneous moral and political judgements and then, only afterwards, come up with the justifications for them.
Brian Orend's The Morality of War is also a superb, very readable introduction to the ethics of armed conflict.
One other book is worth mentioning: Unfollow by Megan Phelps-Roper.
Phelps-Roper grew up in the Westboro Baptist Church but eventually left. This is an extraordinarily perceptive observation that she made retrospectively:
‘Doubt causes us to hold a strong position a bit more loosely, such that an acknowledgement of ignorance or error doesn’t crush our sense of self or leave us totally unmoored if our position proves untenable. Certainty is the opposite: it hampers enquiry and hinders growth. It teaches us to ignore evidence that contradicts our ideas, and encourages us to defend our position at all costs, even as it reveals itself as indefensible. Certainty sees compromise as weak, hypocritical, evil, suppressing empathy and allowing us to justify inflicting horrible pain on others.’
This immediately puts me in mind of organisations like Hamas. Their certainty comes from their view that everything they do is mandated, even commanded by God.
But, thinking of characters like Netanyahu and Putin, secular ideologies can also be construed in exactly this way.
As to where to go next, it would be these three books. Already have the first two but am thinking of also acquiring Shlaim's history.