The article was inspired by the text Significatio della Comunione contained in Benedict XVI’s posthumously published book Che cos’è il cristianesimo. Quasi un testamento spirituale, which caused a considerable stir in ecumenical circles and was usually interpreted as an expression of the senior pope’s opinion about the impossibility of intercommunion with Protestants. The author tries to read the meaning of this text in a different way, considering it as Benedict XVI’s last voice in the theological discourse, giving inspiration for further research. The article consists of two main parts. The first part presents the theological background of the issue of the Mass as a propitiatory sacrifice in three dimensions relevant here: the biblical and theological basis, the essence of the Catholic-Protestant controversy in this regard, and the rapprochement on the path of contemporary ecumenical dialogue. The second section is a chronological overview of Ratzinger’s theological contribution to the resolution of this controversy from the 1960s to the end of his pontificate. Here we see that this theologian’s work is not only in the line of the theological avant-garde breaking the stereotypes of the thinking of the time of the Reformation split, but also has an original contribution to the search for a path toward Eucharistic communion. The peculiarity of Ratzinger’s theology here is, above all, a unique theological innovation drawing from fidelity to Tradition – there is no search for irenic shortcuts towards unity, but rather a diligent search for truth in the sources of Revelation, as summarized in the text mentioned at the beginning, published after his death.