For mP:
Examples of Christians being persecuted by Romans:
Meanwhile, in the case of those who were denounced to me as Christians, I have observed the following procedure: I interrogated these as to whether they were Christians; those who confessed I interrogated a second and a third time, threatening them with punishment; those who persisted I ordered executed. - Pliny the Younger
Pagans wiped out by Christians:
We command that those persons who follow this rule shall embrace the name of Catholic Christians. The rest, however, whom We adjudge demented and insane, shall sustain the infamy of heretical dogmas, their meeting places shall not receive the name of churches, and they shall be smitten first by divine vengeance and secondly by the retribution of Our own initiative, which We shall assume in accordance with the divine judgment (28 February 380). - Theodosian Code
Jewish communities massacred by Christian Pogroms:
One of the most infamous of the pre-expulsion pogroms took place in York on the site known as Clifford’s Tower. In March 1190, six months after the coronation of King Richard I, the city caught or was set on fire. Under cover of the fire a mob targeted the Jews. The family and friends of the leading Jew called Baruch* were attacked and killed and his wealth looted. - York Pogrom, 1190
Christians killing Muslims:
"The aim of Christianity is not to fill the earth, but to fill heaven. Why should one worry if the number of Christians is lessened in the world by deaths endured for God? By this kind of death people make their way to heaven who perhaps would never reach it by another road." (to be fair, Humbert is speaking of the deaths of the crusaders, not the victims - jg) - Humbert of Romans in the 1270s
Muslims killing Infidels:
Once [Abu Bakr] crushed the rebellion [against Islamic rule within Arabia], Abu Bakr may well have decided to alleviate internal tensions by employing the unruly energies within the ummah [Muslim community] against external foes. Whatever the case, in 633 Muslim armies began a new series of campaigns in Persia, Syria and Iraq . - ( Jerusalem: One City, Three Faiths , by Karen Armstrong, New York: Ballantine, 1997, p. 226).
Catholics and Protestants killing each other:
Despite efforts to bring about a resolution to the conflict during the 1970s and 80s, terrorist violence was still a problem in the early 90s and British troops remained in full force. More than 3,000 people have died as a result of the strife in Northern Ireland
Read more: The Northern Irish Conflict: A Chronology | Infoplease.com http://www.infoplease.com/spot/northireland1.html#ixzz2N9TN3EyN
Isreali restrictions in Palestine persecute Christians, Jews and Muslims:
http://www.un.org/apps/news/story.asp?NewsID=25426&Cr=middle&Cr1=east
Religious persecution around the world:
http://www.un.org/News/Press/docs/2004/hrcn1072.doc.htm