Your friend saw this resource on bethinking.org and thought you should see it:
An Honest Look at the Good and Evil of Christian History
John Dickson's book 'Bullies and Saints' examines the dark and light of church history.
See the full resource online by visiting bethinking.org:
https://www.bethinking.org/is-religion-harmful/bullies-and-saints
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bethinking.org is a collection of resources which aims to make sense of the big questions of life about God, Jesus and Christianity.