The article is concerned with the way in which Christian preachers discursively handle the categories of 'us' and 'them' in their sermons. The author points out that there are two different groups of 'them' in the sermons: (1) sectarians, and (2) unbelievers. According to self-categorisation theory, members of 'them', which comprise the so-called 'out-group', are often presented negatively, in sharp contrast to the positive self-presentation of members of the 'in-group'. And since sectarians comprise the genuine 'out-group', there is no problem for Christian preachers to talk about them. However, with respect to the latter group the situation is somewhat different. The problem for the preachers consists in the fact that their aim is not to defeat the unbelievers, but to make them believers. By using membership categorization analysis, the author shows how they discursively solve the problem of differentiating unbelievers and believers in such a way that no strict border splitting 'us' and 'them' is created. Such distinction might be undesirable for the preachers endeavouring to coax the unbelievers to believe in God and the believers to help unbelievers find the proper life course, since a definite border between 'us' and 'them' breeds the negatively presented 'out-group' and positively self-presented 'in-group'.