Festival is a performative dimension of cultural praxis that strengthens bonds of cohesion in society. Festivals are also an integral part of religious praxis. They have the potentiality of bringing its adherents and non-adherents together thus creating and sustaining social communion among them. This reality of sustaining social communion confirms an important function of religion in society with particular reference to its social integrative effects. Therefore, this article assesses how religious festival, Christmas, fosters social integration among Igbos in Nigeria. On a related note, many Igbos, see Christmas festival as unique occasion for them to visit their communities; attend meetings of their associations and/or town unions and consolidate family ties. These are opportunities for building social integrations, otherwise denoted as social communion in this research. This work makes use of critical analysis of relevant texts and questionnaire survey methods as means of gathering materials and data for this research. In view of understanding how Christmas festival aids social communion among the Igbo ethnic group, the theories of structural functionalism, social capital and social integration are being utilised as theoretical frameworks for this study. Finally, this study avers that religious festival cements social communion between the Igbos in Calabar Metropolis and their ancestral communities.