There is also a gorgeous sung Compline at Christ Church in the U District, Wednesday nights at 9:30pm, free. Some of the same singers from St. Mark's.

There are SO many wonderful choral groups of so many styles in Seattle! The Seattle choral community is vast and friendly. Check out the FB page "Greater Seattle Choral Consortium" where there are dozens of ensembles listed - many of their directors meet regularly to strategize and cross-promote choral culture.
theesoterics.org is a group that I sing with that does newly composed and non-religious works often - truly moving experiences for sure!

See Barbara Ehrenreich's Dancing in the Streets for a fun read about the community/connection building effect of communal movement. Then, think of, yes, coordinated breathing among singers, which does definitely lead to coordinated heartbeats, which creates "one body" at least in the chorus, and probably in the audience, too. Finally, add in that most "experts" on spirituality, and most people who try to talk about spirituality mention the concept of "connection" as basic to "feeling spiritual" and there you are--having exactly the intended experience, whether or not you're hearing the music in a "spiritual" context.

I think there always is something mythological about music, all music. Like many other art forms, music is a way for us to explore those deep truths...who we are, why we're here, what's important about life.

You can tell a lot about about a culture by the songs they sing. Song has always been the way to say really, really important things (why else would there be so many songs that all say, "I love you," otherwise?)

When you listen to Josquin des Prez, you're able to look back into the hearts and minds of the 15th century. Not perfectly, of course, but in a way that does feel like you are coming to know the minds and hearts, on some level, to some degree, of people who have been dead for 500 years, which is a miraculous thing. And potentially spiritual and transcendental too. For a moment, you can step outside of the moment and touch something of the eternal, which is absolutely part of what des Prez and other composers of the time were attempting to communicate.

Two words: Tallis Scholars. A tremendously gifted ensemble whose vast library of recordings is a treasure for choral music enthusiasts. For example;
https://youtu.be/YDOENZediM8