‘Faith’ (pistis) is a key term in early Christianity. It not only describes the self-understanding of an individual Christ-follower, but also operates as the social marker of the Christ-groups. Rather than adding to the renaissance of studies on faith in recent years, this article seeks to illuminate what faith is by focusing on the phenomenon of doubt, broadly understood. After some linguistic reflections, the article identifies six basic types of doubt in early Christian writings and then compiles eighteen coping strategies and patterns of resilience reflected in the most prominent texts. The article is not an attempt at systematizing early Christian reflections on doubt but is rather a cornucopia of insights into how the first Christian theologians talked about doubt, dealt with it, and tried to overcome it.