Although the ‘Christological question’ is not the center of Contra Eunomium I, it is significantly present in the text, since the Trinitarian perspective directly affects Christology. As Gregory himself affirms: the generation of the Logos is the same question as that of Christ’s divine filiation (CE I 288–291 [GNO I, 111–112]). The present study focuses on the analysis of the Christological elements of CE I, emphasizing their convergence with the core of Gregory’s thought. Although the references to Christological and Soteriological issues are discreet and scarce in CE I, they are important. For Gregory, what is at stake in the debate with Eunomius is not only the Trinitarian faith but also the radical novelty of Christianity as opposed to Judaism, the mediation and the reign of Christ, and Christ as radiance that manifests the Father’s glory. It is also Gregory’s entire mystical theology that reacts against Eunomius: only if Christ is God is he deserving of that mystical love that converts the soul into spouse of the Word and leads one out of himself in a sobria ebrietas, in a tireless search without growing tired.