I don't think anyone of you is getting the point at all.
Just imagine how communities were, say, two or three thousand years ago. People largely lived in tribal communities, isolated from one another and usually at war with one another. There were probably thousands, if not millions of such communities all over the world.
What unity was possible between say a village in Africa, a community in Asia and another in Europe? The only uniting factor was religion. What unites people even today, in such a large and diverse country like India? It is religion.
Geography is too limited a factor. So are race and language. What is it that transcends all these limitations to create a sense of kinship? It is religion. Religion was the only 'notional' factor or belief that brought a link, a bond to very different groups of people around the world.
Its a different matter that they manage to fight between themselves sometimes, which according to me is neither here nor there. Without religions, there would be millions more fighting among themselves. Millions would have never united in the first place.
Today, broadly between 5 billion people out of the 7 billion, we have just about 4 religions. This is a very significant unifying factor.
Besides this unity, religions have also been largely responsible for the humane qualities that we associate with civilized people. Without religions not just unity but also the concepts of cooperation, truthfulness, mutual respect, self control, fidelity and so on would not have arisen and been enforced.
Religions have been largely responsible for any kind of social order, law and self discipline. Religions without doubt, have been the single civilizing factor in the word over thousands of years.
The fact that some religious groups fight among themselves is besides the point. What the situation would be without them is the point.