St. Thomas Aquinas on the necessity of faith in the Blessed Trinity for salvation

Abstract

This dissertation is an exposition of St Thomas Aquinas on the question of why believing the doctrine of the Trinity is necessary for salvation. We argue that Aquinas thinks assent to the doctrine of the Trinity by living faith saves through giving the believer an obscure knowledge of what God is in himself. We can come to heavenly beatitude, which is the full knowledge of God in himself, only through loving God in himself during our life on earth. During this life, unless a person holds to the doctrine of the Trinity by divine faith, then they do not know God as he is in himself and therefore cannot love him as he is in himself. But if a person does hold to the doctrine of the Trinity by divine faith in this life, then they do know what God is in himself, albeit obscurely, and therefore they can love him in this life and merit the face-to-face vision of him in the next. This, we will argue, is the primary reason why, for Aquinas, explicitly believing the doctrine of the Most Holy Trinity is necessary for salvation. We will also argue that, for Aquinas, the need to know God obscurely in this life to merit eternal life is the reason why it was fitting for God to deliver the doctrine of the Trinity through the verbal teaching of Jesus Christ. Similarly, we will argue that this need explains why God infuses the spiritual gift of Understanding in all who are in a state of grace. Aquinas’ insights on this topic can enrich our understanding of the place of the doctrine of the Trinity in the devotional lives of Catholics.