I myself find it absolutely impossible to believe that Mahler was
irreligious, and would be more charitable than those who argue that his
change of religion showed that he put material gain above the needs of the
spirit.  Rather I feel that it shows that he was not concerned with the
form of religion:  he realised that all of the different religions on earth
were but different facets of the same God.  The Hindu parable of the blind
men and the elephant tells us that we are blind to the glory of God and so
different people may feel different sides of Him (or Her) and think it is
a different God:  whereas in fact it is not.

I think that Mahler realised there is one God, "in the sense that God can
only be understood as love" [Can anyone give the primary source of this? It
is quoted in the notes to the Horenstein/LSO 3rd Symphony]; he was content
to use whatever religion was convenient as they all reach the same end.
Hence he felt able to set the doxology - and indeed, the whole of a hymn
to the "Creator Spirit" - along with a text from "Faust" that presupposes a
Christian belief (The imagery in the text is all Christian, e.g.  the first
penitent's plea of "Bei der Liebe, die den Fussen / Deines gottverklarten
Sohnes / Tranen liess zum Balsam fliessen" - "By the love, that from the
feet / Of thy Divinely-transfigured Son / Let tears as balsam fall" and so
on) in his Eighth Symphony; but not the "Credo".

Could the passage that caused the objection in the "Credo" not be "Et
UNAM sanctam, Catholicam Apolisticam Ecclesiam":  the implication of
just one acceptable church - or going back to the Latin root, one
acceptable community - go against his conviction.  After all, he had himself
experienced discrimination from those who believed that there was only one
acceptable community:  he was a social outcast from the start as only the
eldest son of a Jewish family could legally marry at this time - and so his
father was regarded as illegitimate.  Indeed, it could merely be that he
objected to the formalism of the church implied in the mass - after all,
"Veni, Creator Spiritus" is hardly a conventional formal hymn setting!

It is my view that the principal tenet of Mahler's religion was a kind
of transcendentalism, a feeling that there is something beyond but that
this is manifest in unseen ways all of the time; and also that God is one,
however he is worshipped.  Hence the use of the Nietzsche text of "Das
Trunkene Lied" to convey a spiritual message despite the fact that this
went against all religious protocol - and as for following it with the line
"Es sungen drei Engel einen sussen gesang" amidst Matins bells.....!

Sam Kemp