Does Religion ever unite people across different ethinic and racial groups

I think it can. In my church we have people of all racial and cultural backgrounds, we even have people from India, Laos, and Iraq... although the majority are white. But there are mennonite churches all over the world with people from all different backgrounds, and there are many other types of churches that are worldwide as well. I feel that my religion unites me to people of all races and ethnicities and cultures. It has to, it is one of the only things that can. When Jesus reached out to the Samaritans, He shocked and even disgusted some of the Jews, who believed that Samaritans were the scum of all scum. Jesus even went as far as to tell the Jews that the Samaritans were their neighbors that they should love as themselves. In doing this, He opened Christianity up to people of all ethnicities, to worship together. It is people and their discriminatory sinful nature that divides. Once that division is successfully accomplished, for instance, the division of African-American and Caucasian churches in America, it is for people hard to turn away from the worship style that they know just for the namesake of unity. It is hard to leave your comfort zone.

Of course it unites people of diverse ethnicity, race, nationality, language et al. Look at Pan Islamic and Pan Christian movements. They are beyond the boundaries of nation, race, ethnicity and language. My country India is as diverse as it can get. We have people of every imaginable hue and colour. From this diverse diaspora, many Anglo-Indian Christians and indigenous have migrated and settled in Christian nations of the west and Australia just because as Christians, it was easy for them, aided as they were by a network of churches. Similarly, after the creation of Israel, majority of Indian Jews have migrated and settled to that nation…their Indian language, colour, race posed no problem at all. Similarly you have Islamic brotherhood irrespective of the land from where they come. Regarding Bangladesh now, as a Bengali myself, I feel Bangladesh in 1971 was an aberration in the Islamic world. Call it the Bengali psyche or whatever, Bangladeshis of that time were more Bengali than Muslim. Women wore sarees and did not use burqa, dressed up and wore bindis, participated with men with equal enthusiasm in all things starting from literature to politics, Tagore and local folk culture was much revered, universities were more centres of intellectual fountainhead rather than religious insularity…and many more differences which helped in the birth of Bangladesh. Their very stand that as Bengalis, it was their birthright to use Bengali and not Urdu, is a landmark movement in modern history. However, all that is much changed now and Bangladesh is gradually slipping into the archetypal Islamic mould, paying obeisance to Saudi Arabia and clutching on to the Sharia.

I say it depends on the religion, location, and time period. Nowadays, it can unite people across a spectrum. Buddhism, Paganism, Christianity, and Islam have done this in alot of places -- and in this past year, no less. I'm sure this is also the case for other religions. Religion can also be the excuse (or cause) of division though, as you've pointed out. And that is also still the case in many places today. Generalizations in either positive or negative directions seem biased and silly to me, but we're all entitled to our opinions.

Actually it does the contrary most of the time because people always think their religion is the only one right. People don´t know yet to respect differences.

Religion is a very important variable in the identity construction process. The history highlights however, that no religion is able to unite the people across different ethnic and racial groups, except when other iterests are supporting such attitude. World's greatest conflicts were fought between Christians (with the exception of Japan). Despite of claiming to be Christian (while praying to God for the conflict to end) both the Axis and the Allies bombed their fellow Christians from Italy, Germany, France, England, Hungary, Russia, Poland, Romania, Serbja, Croatia, etc destroyed churches and chapels, killed millions of co-believers, and even priests, nuns, etc. Religion can't unite people because religion is divisive by default. Religion can't unite people, or groups of people, because each group will try to impose its PRIMACY over others (for instance, the reason why Roman Catholic Church splited from the Orthodox Church). The primacy of a ethnic, racial, interest, etc group over other is a part of the human civilisation. Humans aren't equal. Groups inherit this characteristic.