Dei Filius is the incipit of the dogmatic constitution of the First Vatican Council on the Catholic faith, which was adopted unanimously on 24 April 1870.
The constitution set forth the teaching of "the holy Catholic Apostolic Roman Church" on God, revelation and faith.[1]
The draft presented to the Council on 8 March 1870 drew no serious criticism. But a group of 35 English-speaking bishops, who feared that the opening phrase "Sancta Romana Catholica Ecclesia" might be construed as favouring the Anglican Branch Theory, raised objections to this expression, "Holy Roman Catholic Church". They proposed that the word "Roman" be omitted out of concern that use of the term "Roman Catholic" would lend support to proponents of the Branch Theory. While the Council overwhelmingly rejected this proposal, the text was finally modified to read "The Holy Catholic Apostolic and Roman Church".[2]
The opening words "Sancta Romana Catholica Ecclesia", were voted on on three separate dates. On the first occasion, when this chapter alone was considered, two votes concerned the opening words. The first was on a proposal by a few English-speaking bishops to delete the word "romana", thus changing "Sancta Romana Catholica Ecclesia" (The Holy Roman Catholic Church) to "Sancta Catholica Ecclesia" (The Holy Catholic Church). This was overwhelmingly defeated.[3][4]
The second vote, held immediately afterwards, was on a proposal to insert a comma, so that "Sancta Romana Catholica Ecclesia" (The Holy Roman Catholic Church) would become "Sancta Romana, Catholica Ecclesia" (The Holy Roman, Catholic Church). This too was defeated, though not as overwhelmingly as the first proposal.
In a later vote, held on 12 April 1870, the text as a whole, which preserved the same opening words, was approved with 515 affirmative votes (placet) and no opposing votes (non placet); but there were 83 placet iuxta modum votes, asking for retouches, many of them regarding the opening words of chapter I.[5][6]
In view of the reservations thus expressed, the text presented for a final vote and approved unanimously on 24 April changed the order of the words and added "Apostolica", so that "Sancta Romana Catholica Ecclesia" became "Sancta Catholica Apostolica Romana Ecclesia" (The Holy Catholic Apostolic Roman Church).[6][7][8]