Migration has become a burning issue of the contemporary world, while immigrants are the “incarnation of outsiders”. Although research shows that most Europeans support open Europe, spreading moral panic is one of the more frequent responses to migration. Politicians and the media, especially those on the right and the far right side of the political spectrum, try to represent immigrants as a security problem and every other kind of problem for all, even potential, recipient countries. Xenophobophilia, i.e. the political exploitation of xenophobic tendencies in the general population, is on the rise together with xenophobia, which forms a kind of social perpetuum mobile of the third kind. The public discourse often associates immigrants coming from predominantly Islamic countries with terrorism, as if they were Islamists, thus instilling the fear of mass migration from the Islamic world and of possibly devastating Islamic influence on the Christian cultural foundations of contemporary immigration societies. In this context, the question of whether traditional immigration countries as well as new or potential ones are ready and able to face the contemporary challenges of religion. In essence, the dynamics of the relationship between immigrants and the receiving society and the need for its understanding make the issue of religion, among other factors, both complex and unavoidable in migration research. This connection was mainly observed either from the perspective of the sociology of migration or the sociology of religion, which determined the focus and aspect of linking the two phenomena. Therefore, this paper first offers a brief insight into previous sociological research from both perspectives, and then tries to pose the issue of sociological research of the relationship between religion and migration with a study conducted in Croatia on a representative sample of adult citizens. An insight into theoretical and empirical research of this relationship shows that they are socially and historically determined in many facets. This is obvious in the differences in the topics that sociologists focus on and which arise from the social and historical context within which they are being explored. Contextual differences in multi-national research represent a problem for researchers, confronting them with theoretical limitations and methodological challenges. Problems of terminological ambiguities arise in these situations, which are further complicated by comparative research and the narrowing of theoretical and analytical focus on theories of competitive threat both on an individual and macro level. As the social and historical context in a way determines the subject and methodology of research, knowledge of it is important for the analysis and interpretation of research results. This is also observed in the research of symbolic boundaries towards immigrants and their possible transformation into social boundaries. When the relationship between symbolic and social boundaries is thought of in connection to contemporary mass migration, the symbolic boundaries are expressed in individual attitudes towards immigrants, and social boundaries can be recogvnised in the consequences of these attitudes: materialised in disorderly and poor living conditions in refugee settlements at the borders, fencing of state borders with walls and razor wire, formed in immigration policies, expressed in active resistance to the establishment of centres for asylum seekers in local communities, etc. In this context, where most of the immigrants come from predominantly Muslim countries to a predominantly Christian Europe, religion is seen as a symbolic boundary that needs to be the focus of research. Starting from this point of view, and from the fact that the importance of religion as a symbolic border, as well as other ethnic markers and cultural features, varies from society to society, Croatian society makes a good example for several reasons. Croatian society has a long history of multi-ethnicity and multi-confessionalism within multi-ethnic and multi-confessional states. In the past, ethnic differentiation primarily relied on religion as a cultural symbolic boundary, and in many respects it still does so. The transitional period and the new-found state independence were characterised by strong national homogenisation and a war at the end of the 20th century, and by joining the European Union, the population of the traditionally emigrant society was presented with the possibility of an even easier emigration, but the potential for an inflow of immigrants also increased. Croatia’s state borders became more open than ever for bi-directional population migration, which raises the question of whether the symbolic and social boundaries followed the same transformation. In addition to answering this question and given the social context in which religiousness is strongly expressed, and the arrival of immigrants is more of a possibility than a reality, the main aim of the research was to try to determine whether some of the examined dimensions of religiosity (religious self-identification, confessional self-identification and religious practice) can be considered as predictors of Croatian citizens’ attitudes toward (potential) immigrants. The empirical research using the survey method was conducted from June to September 2009 on a representative stratified sample of 1300 adult citizens of Croatia. In addition to socio-demographic characteristics of respondents and their self-estimated socio-economic status, used as independent control variables, and expressed political orientation of respondents as an additional control variable within the regression analysis, within the framework of the research from the wider survey questionnaire, the analysis uses instruments related to major independent measures, the dimensions of religiosity, instruments related to independent constructs, a measure describing the attitude of the relation between religious and national identity, and a measure describing the social distance towards religious groups, and instruments related to dependent constructs describing attitudes towards foreign (immigrant) workers. In relation to the posited research questions of whether there is a connection between the examined dimensions of religiosity (religious self-identification, confessional self-identification and religious practice) as independent variables and attitudes towards foreign (immigrant) workers, the expressed social distance and the perception of threat of immigration, as dependent variables, a connection has been determined. Analysis of variance (ANOVA) determined statistically significant differences in average social distance towards foreign workers according to all three dimensions of religiosity. Respondents who self-identified as most religious, as “convinced believers”, express a statistically significantly greater social distance towards foreign workers than the “religious”, “unsure and indifferent” and “non-religious and opposing religions” respondents. Those who never attend church express a statistically significant smaller social distance towards foreign workers than those who attend it rarely, on a monthly or weekly basis, or even more frequently. Differences in confessional identification show that those without confessional affiliation are statistically significantly less likely to express social distance towards foreign workers than those that identified confessionally, i.e. Catholics and others. Using the analysis of variance, statistically significant differences in average attitudes towards immigrant workers were determined and described by the factor construct of the sociocultural immigration threat, according to all three researched dimensions of religiosity. The results show that those who self-identified as “nonreligious and opposing religions” express a statistically significant lower degree of perceiving the sociocultural immigration threat than the “convinced believers” and “religious”. Those who never attend church perceive immigrants as less of a sociocultural threat than those who attend it rarely, on a monthly or weekly basis, or even more frequently, to a statistically significant degree. Differences in confessional identification show that those who identified as Catholics are statistically significantly more likely to view immigrants as a sociocultural threat than those without a confessional affiliation. When it comes to average attitudes towards immigrant workers described by the factor construct of the immigration socio-economic threat, analysis of variance found statistically significant differences only with respect to the religious self-identification of the respondents. The “religious” accept the views that describe this factor to a statistically significant greater extent than the “convinced believers” and the “unsure and indifferent”. Finally, a hierarchical regression analysis of predicting social distance towards foreign (immigrant) workers has been carried out in four steps (models), with respect to the examined dimensions of religiosity, with respect to attitudes towards the connection of religious and national identity, and with respect to the expressed social distance towards members of other religions (non-Catholics), and with control for socio-demographic variables (gender, age and education) and variables of self-estimated socio-economic status and political orientation of respondents. Religious self-identification within the first model (β = -0.118) proved to be a significant predictor, and the result suggests that those who identify as more religious are more inclined to express greater social distance towards foreign workers. After the inclusion of the other two religiosity indicators in the second model, religious practice and confessional self-identification, the result shows that those who identified as Catholics, unlike those who expressed that they do not belong to any confession, are more inclined to express a greater social distance towards foreign (immigrant) workers (β = -0.145). In the third model, a variable was added which describes attitudes to the connection between religious and national identity as a construct, which revealed that this variable contributes the most to the explanation of the dependent variable (β = 0.294), demonstrating that those who are more in agreement with the statements describing that construct tend to express greater social distance towards foreign workers. In the fourth regression model, explaining 49.3% of the variance of the criterion variable, the addition of the variable of social distance towards members of other religions (non-Catholics) explains an additional 32.7% of the variance, and this variable proves to be by far the most significant predictor (β = 0.644). From the results obtained, it follows that social distance towards foreign (immigrant) workers is more likely to be expressed by those who evaluate their socio-economic status as inferior, those who identified themselves as Catholics, unlike those who expressed that they do not belong to any confession, those who hold the view that religious and national identities are closely related, and especially those who are inclined to express social distance to members of other religions (non-Catholics). It is concluded that the researched dimensions of religiosity have been shown, as is the case in some other studies, as significant predictors of attitudes toward (potential) immigrants. In addition, since the respondents who identify themselves as more religious are more inclined to xenophobic attitudes than those who identified as less religious or non-religious, expressed religious identity, especially confessional identity, is shown to be a symbolic boundary towards (potential) immigrants in the Croatian society, and this is also indicated by the finding that those who accept the view that the religious and national identity are closely related and those who are inclined to express social distance to members of other religions (non-Catholics) tend to express a high social distance towards foreign (immigrant) workers. The results of the research also point to the validity of the assumption that highly expressed religiosity, especially confessional identification, points to a wider social and cultural identity to a large extent.