Explain the Hallelujah lyrics to me

So many people have done this song, and now Pentatonix (spelling) is famous for it. Lyrics make no sense, nor do I see why it's played during Christmas


Hallelujah
Jeff Buckley
Lyrics
Well I heard there was a secret chord
That David played and it pleased the Lord
But you don't really care for music, do you?
Well it goes like this: the fourth, the fifth
The minor fall and the major lift
The baffled king composing Hallelujah
Hallelujah [x4]
Your faith was strong but you needed proof
You saw her bathing on the roof
Her beauty and the moonlight overthrew you
She tied you to her kitchen chair
She broke your throne and she cut your hair
And from your lips she drew the Hallelujah
Hallelujah [x4]
Baby I've been here before
I've seen this room and I've walked this floor (you know)
I used to live alone before I knew you
And I've seen your flag on the marble arch
And love is not a victory march
It's a cold and it's a broken Hallelujah
Hallelujah [x4]
There was a time when you let me know
What's really going on below
But now you never show that to me, do you?
But remember when I moved in you
And the holy dove was moving too
And every breath we drew was Hallelujah
Hallelujah [x4]
Maybe there's a God above
All I've ever learned from love
Was how to shoot somebody who outdrew you
And it's not a cry that you hear at night
It's not somebody who's seen the light
It's a cold and it's a broken Hallelujah