This thesis will examine how traditions and rituals, pre-Christian and pagan, were integrated, reordered, and flourished in Christian doctrine before the Reformation, and how these phenomena may have influenced the symbolism and representation of pre-Christian rituals in Irish and Norse medieval literature—specifically in the evolution of legendary characters Finn Mac Cumhaill and Sigurðr, following their full participation in an otherworldly meal and acquisition of otherworldly knowledge. Pre-Reformation Christianity shared more similarities with pre-Christian religions than post-Reformation Christianity does, and several Christian teachings rise out of pagan origins and philosophy. Modern scholarship, however, tends to view these myths through a post-Reformation lens without demonstrating a deep understanding of pre-Reformation Christianity. This thesis will address how Sacred Tradition, ritual, sacrifice, and mediation through three separate roles—priest, prophet, and king—are paramount in pre-Reformation Christianity, working in union and in equal gravity with Sacred Scripture, facilitating a model of integration. It will address the role of covenant and participation in a sacred meal, binding two parties in kinship and legality, as well as the role of the lady with the drinking cup, in regard to kingship and marriage, as a form of covenant and necessary binding. Lastly, it will address mediation, an obligatory function in many religions beyond Christianity, from the vantage point of the three separate roles. These occurrences will be examined in the Irish literature, with parallels drawn to the Norse tradition and their nuances. Rather than assessing both traditions under the suffocating blanket of Christianity, this thesis will examine the nuances of pre-Christian and Christian integration, present in the subtleties and distinctions of these two traditions. In conclusion, this thesis hopes to provide a glimpse into the Christianity medieval scribes knew intimately, and perhaps shed light on the relationship that pre-Christian communities may have shared with the invisible side of nature—with the otherworld—by means of integration and re-ordering of relationships, through the prism of pre-Reformation Christianity.