I have a view on why Pirsig's words "appear" to be silent on this.
Previously I've gone so far as to suggest there was no place for
religion in the MoQ, at least not the deistic kind. As an atheist I
didn't recognise this as a short-coming initially, to see the MoQ as
re-inforcing the darwinian anti-religion meme, but Sam has been
educating me :-)
Now, I'd say, Pirsig was tactically avoiding too many battlefronts -
simply being neutral where he could be, hypocritical where necessary,
we all do it. In a conservative America, when your aim was to publish
a "great book" or two, would you overtly support an apparently
anarchic / irresponsible movement of peace and love, and overtly argue
any shortcomings in the prevailing conservative religious
establishment - I think not.
I agree he can't spell everything out. He leaves us to draw our own
conclusions. In fact I think most of us who've had time to think about
"quality" can see "faith" at the root of any metaphysics, and love in
his quality interaction metaphors. I think choosing the word "quality"
was his stroke of genius. A deliberately ineffable "quality" we could
all already identify with - not too scientific, not too religious -
and enough rope to hang ourselves with of course.