Community identity is based on birth and belonging rather than on some form of acquired qualifications or accomplishment.
These kind of identities are called ascriptive i.e. they are determined by birth and individuals choice is not involved.
People feel a deep sense of security and satisfaction in belonging to communities.
Ascriptive identities such as community identities are difficult to shake off; even if we choose to disown them, others may continue to identify us by those very markers of belonging.