What to do? That depends on all kinds of factors. As with any situation where some friend reveals that they are in fact some kind of bigot. Because objecting to that line in that context is bigotry.

Long introductions to songs aren't a good idea, whether they are political or religious. Let the song carry the message, if there's a message.

And I'm with you all the way on the cultural vandalism in Catholic Masses, GUEST (Tom?). Latin I can do without (though I really miss it when I'm at Mass in a non-English speaking country), but the timid slow strum and tambourine "folk masses"...