The article contributes to the ecumenical debate on the relationship between the Church of Christ and the Catholic Church, a debate that followed upon the 2007 publication of a series of Responses on Vatican II ecclesiology by the Congregation for the Doctrine of the Faith. The author seeks to develop a critical understanding of subsistit in that is both historically and theologically sound. An in-depth study of the redaction of Lumen gentium no. 8 leads to the conclusion that the council did not understand the Latin verb subsistere in terms of essence (esse).