As long as there has been religion, there has been conflict over which is the true religion. Humankind has been going to war over gods and customs for tens of thousands of years. Sometimes religion is a convenient mask for secular disputes over land, such as in the Israeli conflicts with Egypt and Syria. Sometimes it is the backdrop of cultural conflicts like terrorist activity in Afghanistan and Pakistan, or an old grudge like India and Pakistan. From ancient times to suicide bombers on the streets of Peshwar, the major religions have struggled against each other over claims of being the one true religion.
However, there are sects out there that embrace a different view, which recognizes the grains of truth in every creed. In these troubled times for the faithful, there is a lot to learn from such traditions, or more specifically, the Bahai. As science pulls at the ties that bind all religions, the Bahai faith recognizes the wisdom of the prophets of all religions, from the line of Abraham, to Krishna, Buddha, Jesus, and Muhammad. They preach the unity of all humanity, and strive to know God through prayer, reflection, and service to their fellow man. This seems to be the exact spirit needed in these troubled times.
The Bahai faith was founded in 19th century Persia by Bahá'u'lláh. The primarily Shiite Iranian kingdom exiled him for his beliefs, and he fled to the Ottoman Empire in modern day Turkey. He found no shelter amongst the Ottoman Turks, and he died in a Turkish prison. His son, Abdul-Baha spread the faith throughout Persia, the Middle East, and Turkey, as well as in Europe and the United States. Today there are more than five million Bahai in two hundred countries around the world. Although they are still persecuted by the Iranian Muslim theocracy, the teachings of Bahá'u'lláh are still alive and well in the 21st century.
Preached in Paris
Abdul-Baha spent a considerable amount of his life in prison, freed only after the Turkish revolution of 1908. Afterward, he preached in Paris and many other European countries. The content of his speeches, over a hundred years later, still seems fairly progressive; he advocated equality of the sexes, unity of religion, and the establishment of a world parliament to which nations would surrender some degree of their sovereignty for the good of all. At the time, this was wild, radical stuff, and it bears repeating once more that this was prior to the outbreak of World War I.
"Unite and bring mankind into one shelter beneath the banner of thy protection so that they may become as waves of one sea, as leaves and branches of one tree, and may assemble beneath the shadow of one tent." This seems utopian, as the closest humanity has ever come to achieving such a state is by the violent conquest and the establishment of empires, which invariably fall. The best tool we have to unify peacefully is, simultaneously, the strongest force humanity has ever experienced to keep people apart and set them against each other. It is religion.
History of Religion
The history of religion is full of wars one church wages against another, with each side believing itself to be the one true faith, and the other side to be infidels. Abdul-Baha recognized this and critiqued organized religion, in a 1912 speech in Paris, in pointed terms: "If priests of religion really adored the God of love and served the Divine Light, they would teach their people to keep the chief Commandment, 'To be in love and charity with all men.' But we find the contrary, for it is often the religious clerics who encourage nations to fight. Religious hatred is ever the most cruel."
Because this has always been the case, though, doesn't mean that it always has to be this way. All religions, once all the extraneous aspects such as their institutional structures are stripped away, have more in common than not. Their core tenets are about the search for a better life. Once this fundamental similarity between all faiths is acknowledged, then the previously squabbling factions can unite and work to actually achieve that better life.
Mahatma Gandhi spoke eloquently and at length about this subject, saying "My veneration for other faiths is the same as for my own faith," among other sentiments of religious unity. For his trouble, he was insulted by Winston Churchill, imprisoned, and eventually assassinated. The latter being a fate reserved for nearly every voice advocating for unity and peace, religious or otherwise, from Jesus to Martin Luther King. The most important thing is to not allow that to serve as a deterrent for future efforts to advocate unity and peace, as disunity and war are only inevitable if human beings let them be.
In reaching out across the artificial divisions of religion, it's of the utmost importance that everyone realize that their own faith is not under attack. There is no need for anyone to convert to a new religion -- Gandhi, for one, said to him "the idea of conversion is impossible" -- because all religions will stay, at the most fundamental and important level, the same. It's the process of stripping away the unimportant, troublesome, divisive aspects that will heal religion itself so that all religious people are joined as one.
This is how the conflict between the Christian-influenced West and the Muslim-dominated Middle East can end without the need for one side to wipe the other from the face of the earth. The path to resolution is in theory even easier between these three faiths according to the Bahai clerics, since all three are Judeo-Christian religions, all of which originate with Judaism. In reality, a lot of very difficult and rigorous theology will be necessary to accomplish this. But it can be done, and it may well be argued that it must, for the sake of a peaceful future.