Editor’s Note: The original interview is in German, at Kath.net; the linked image above will take you to an English automatic translation. but here is the key passage of his critique:

The Gnostic opinion that a small leadership elite has special access to the Holy Spirit or that mythologically the Holy Spirit speaks through the “healthy people of intellectually uncorrupted common people” (the “people’s spirit” of the Romantics) has nothing to do with the Catholic faith . There is only one treasure of the Word of God, contained in Holy Scripture and fully preserved and faithfully interpreted in the context of the Apostolic Tradition by the whole Church under the guidance of the Holy Magisterium (cf. Dei verbum 1-10; Lumen gentium 25 ).

One again Cardinal Mueller is a step ahead most commentators. The view that individuals can rightfully identify as something other than the gender or gender orientation willed by God is a gnostic thesis which rejects the true God’s Authorship of Man and Nature, as founded upon goodness, truth, and being, and fixed in its form and nature forever, to which man as a creature must bow down in eternal reverence, respect and care. It is a blasphemy against the Living God to say otherwise. It is despair against God’s vocation in Christ to say otherwise. It is the worst kind of betrayal of the priestly ministry to invoke the Name of God to approve of any other view of humanity. This prevents not only the blessing of the transgendered or sodomitic couples, but also of all relationships of two individual persons, even when these persons present themselves as individuals, which is sinful. There is no distinction between the blessing offered according to ritual and that offered according to spontaneous criteria, because the minister is the same and the same Name of God is named. To say otherwise is gnostic, not just in the sense of a secret knowledge reserved to the few who now have been let by a spirit to realize it, but gnostic also in the sense of divorcing man from his soul, and humankind from its Creator and Lord.