More on the teachings of the magisterium and the teachings of Christ

We need to be precise about the propositions being asserted, so that readers can assess the competing arguments and decide where they believe the truth lies.

Archbishop Chaput, I believe, asserts two propositions,

(1) the validity of the teaching confirmed in Lumen Gentium 25 concerning the conditions under which the ordinary and universal magisterium proposes a teaching on faith and morals infallibly, thus demanding the full assent of faith.  ("Although the bishops, taken individually, do not enjoy the privilege of infallibility, they do proclaim infallibly the doctrine of Christ on the following conditions: namely, when, even though dispersed throughout the world but preserving for all that amongst themselves and with Peter's successor the bond of communion, in their authoritative teaching concerning matters of faith and morals, they are in agreement that a particular teaching is to be held definitively."  Lumen Gentium 25.)

(2) that the teaching that homosexual conduct is intrinsically immoral has been proposed by the ordinary and universal magisterium in a way that fulfills the conditions for infallibility set forth in Lumen Gentium 25, thus demanding the full assent of faith.

Notice that Archbishop Chaput is not asserting that the teachings of the magisterium are necessarily the teachings of Christ.  Only those demanding the full assent of faith are necessarily the teachings of Christ.  Others may be the teaching of Christ, and may even require religious assent of intellect and will despite the possibility that they are not the teaching of Christ.  That, too, is the clear teaching of the Second Vatican Council in Lumen Gentium.

Both of Archbishop Chaput's propositions seem sound to me.  The first one strikes me as simply undeniable from a Catholic point of view.  It is the historic teaching of the Church, frequently confirmed by ecumenical councils, and very explicitly reaffirmed by the extraordinary magisterium at Vatican II.  Some may deny the second proposition, but I very seriously doubt whether a persuasive historical case can be made against it. The teaching is ancient as well as consistent across time and space. If any teaching fulfills the conditions set forth in Lumen Gentium 25, this one pretty clearly does.

If we are precise about what is (and is not) being asserted, it's clear that this is not a debate about whether doctrine ever develops; nor is it a dispute about whether everything that comes from Rome has been authorized by God; nor is it a dispute about whether the non-infallible teachings of the Church (whatever level of assent they demand) are, well, fallible.  Rather, the questions are: (1) Does Lumen Gentium 25 reliably transmit and confirm sound Catholic doctrine, and (2) Does the teaching of the magisterium on the immorality of homosexual conduct fulfill the conditions set forth in Lumen Gentium 25 for a teaching demanding the full assent of faith (i.e., an infallible teaching)?