Consider the rituals (religious or secular) that you observe. What are their effects on the group involved? Do rituals create & strengthen community? How? Do we need rituals to maintain a community?
I would argue that rituals do indeed create and strengthen communities. I would also argue that it is hard to have a true community (unless it is a very small one) whose members do not engage in some sort of ritual on a regular basis.
A community is more than just a group of people who happen to live together in a given area. In order for people to truly constitute a community, they need to interact with one another in relatively consistent ways. The people in the community need to be connected to one another through these interactions. This is where ritual comes into play. Rituals bring people together for a common purpose. They bring people together and allow them to interact in structured ways. This creates a sense of community among people who were not previously connected. When repeated, rituals strengthen the community as well.
I would argue that it is very hard to create a community without ritual. If there are no rituals, there are no events that consistently bring people together in ways that allow them to interact relatively easily. Instead, people have to try to find ad hoc ways to relate to one another. They also have to find occasions on which to come together for a common purpose. Neither of these things is easily done. Therefore, it is very hard to create a community out of any significant number of people without rituals.
We can see the truth of this in many walks of life. Schools try to have things like assemblies and pep rallies to build community among their students. Sports teams have scripted chants and choreographed routines that function as rituals and bind them more closely together. Even families tend to have certain rituals such as preparing and eating meals together or having set nights on which to play games or otherwise have family time.
Thus, we can see that rituals are used by successful communities and it is very hard to have any serious communal feeling without them.