From my perspective, this issue relies on several things. First, we have to look at past examples of different ethnic/religious groups trying to live together in peace. One example is the Armenian/Turkish instance, in which the Armenians, a Christian nation, lived with the Turks, who were largely Muslim. The Armenians were able to live in relative peace for hundreds of years (besides the fact that they were repressed), and finally, in the late 1800s early 1900s, they "rebelled" against the Turks, and the Turks then campaigned what most people call the worst genocide in the 20th century. So from this example, we can see that no matter how hard people try, it is nigh impossible for different ethnic/religious groups to live in perfect peace. Second, I think we have to look at the type of government that a specific nation/country operates under. I think one reason why the US is so "peaceful," at least compared with the rest of the world, is because we are a democratic nation that is protected under a series of checks and balances between the three branches of government. However, if we were to look at Nazi Germany, we see a dictatorship ruled by Hitler. This is bad because if one man rules a nation, then his prejudice presides over the will of the people, and persuades the people in a certain direction, usually for the worse, as shown in pre-WWI with the Turks and WWII with the Nazi party. Once we bring the issue of government into view, I think everything else becomes irrelevant, or at least becomes a second level concern. So my answer would be yes, it is possible for people to live in homogeneity, but under certain circumstances, such as the US. And even then, the US is not perfect. I think democracy is the way to go, most definitely, but it is nearly impossible to impose it on every other country. So I guess my opinion is that homogeinty is possible, but not necessarily probable, given these factors and examples.