When the truth is that there would be no great Western music and certainly no decent choral repertoire without the Catholic faith.
I have such happy memories of performing in a choir and I don't think I'd have got where I am today without all that experience. So my advice to young singers is to either join your school or church's choir or find one in your local area. Choral music at any level teaches you so much about musicianship and blending your voice.
That's the beauty of music. You can take a theme from a Bach sacred chorale and improvise. It doesn't make any difference where the theme comes from the treatment of it can be jazz.