Elaborating on Cognitive Semantics as the theoretical paradigm, the main aim of this paper is to examine the role of metaphor and metonymy in the understanding of the Trinitarian dogma by Christian believers. With respect to metaphor, the author argues that the understanding of transcendental notions by humans is achieved by means of a network of mappings of the human domain onto the domain of the divine. Thus, the Trinitarian dogma is explained in relation to two root metaphors: HUMAN~GOD and GOD~HUMAN, whose submappings and idiosyncrasies are explained and exemplified in detail. On the other hand, the author also examines the metaphorico-metonymic coherence in the dogma, i.e. the way in which some submetaphors are related to specific metonymic instantiations. (Noelia Jiménez Martínez-Losa and Francisco Ruiz de Mendoza)