The compartmentalisation of distinct disciplines limits the opportunities for teachers to work in a collaborative multidisciplinary manner. Workshops such as 'Saviour Siblings' from the Epistemic Insight Initiative encourage students to consider big questions from different perspectives and thus provide a bridge between the religious education (RE) and science curricula at key stage 4 (ages 14-16). This article reports on a collaborative teaching intervention between science and RE lecturers on a secondary PGCE initial teacher education programme. Discussing big questions with their peers proved to develop trainee teachers' beliefs about the power and limitations of science and the value of considering a diverse range of disciplinary perspectives.