In the wake of the Lutheran‐Catholic Joint Declaration on Justification, this essay attempts to explore ecumenical convergences in the writings of Thomas Aquinas and Martin Luther on the question of justification. Specifically, this essay takes the recent Finnish uncovering of the theme of theosis in Luther's work and probes Aquinas' Summa Theologiae for similar themes of ontological participation of the human in the divine. I first display Aquinas' doctrine of God and show how human participation in the Trinitarian life is (...) written into the structure of his account of God. I then show how Aquinas' understanding of participation informs his analysis of the virtues. Finally, I present some of the Finns' findings on Luther and examine covergences with Aquinas. Overall, I suggest that language of participation can help overcome the overdrawn contrast between Aquinas' account of the virtues and the forensic interpretation of Luther. (shrink)