Faithfulness or allegiance to a cause or institution is called:

Loyalty is defined as a strong feeling of support or allegiance to someone or something, such as a cause, institution, or individual. In many contexts, loyalty entails a commitment to uphold the values and interests of that particular entity, often leading individuals to act in its favor even in the face of challenges.

This concept can be seen in various professional settings, where employees demonstrate loyalty to their organization through their dedication, ethical behavior, and willingness to represent the institution positively. Loyalty often builds trust and strengthens relationships within teams and organizations, which is crucial for a harmonious working environment.

While the other terms—duty, devotion, and integrity—carry their own significant meanings, they do not encapsulate the specific notion of allegiance as succinctly as loyalty does. Duty refers more to an obligation or responsibility, devotion suggests a deep commitment often associated with love or passion, and integrity pertains to adherence to moral and ethical principles. Thus, loyalty distinctly highlights the allegiance to a cause or institution, making it the most fitting answer.