This thesis is a work in practical theology that examines the tension between two realities. On the one hand, there are the stated policies of the Presbyterian Church of Aotearoa New Zealand (PCANZ) that encourage its members to live out a diverse life together. On the other hand, there is the reality confirmed in my data that PCANZ congregations reflect ethnic homogeneity rather than diversity. Although increasing sociological research about ethnic relations within religious and non-religious contexts overseas has contributed to a growing interest in this area, within the New Zealand context there has been very little study that includes a theological framework for considering such relations. At heart, my study observes the extent to which the ethnic composition of congregations is influenced by people's theological understanding of the church and of their Christian identity, as opposed to tendencies affirming their ethnic/cultural identity. My research explores the challenges and the richness of the relations of parishioners and ministers to reveal how their theological and ethnic aspirations characterise the communities to which they belong. To understand the context and experiences of those in PCANZ congregations, I adopt a qualitative methodological approach that incorporates a combination of strategies. It requires analysing details from congregations about ethnic representation of members, ministers, attendees at worship services and leadership groups as well as of surveys and interviews of adult parishioners and ministers. My findings reveal that people's own ethnic assumptions and preferences have been more influential than any theological aspirations they may hold for themselves and the church, resulting in the homogeneous reality of their communities. I offer reasons why this is theologically inadequate, and what might be done to change it.The unconsumed burning bush, the emblem of the PCANZ, is a sign of the mystery of God that speaks of hope to God's people. My thesis title, 'Ethnic Flames of the Burning Bush', conveys the complexities and richness of ethnic relations in the PCANZ that do not seek to consume it; rather to enhance its hopeful witness of unity in diversity.