The Prophet Muhammad's treaties with the Christians of his time, which John Andrew Morrow has rediscovered in obscure collections and often newly translated, uniformly state that Muslims are not to attack peaceful Christian communities, but defend them "until the End of the World." Authored by the Prophet himself, they represent a third foundational pillar for Islam outside of Qur'an and hadith. The "Covenants Initiative" within the book represents a movement by Muslims, both prominent and unknown, in support of Christians under attack. 
For scholars, this book provides much difficult-to-obtain material: facsimiles of primary sources in Arabic and Persian; corrected versions in modern Arabic typescript; and alternate translations.  
More information at Angelico Press.