I don't really think Living on a Prayer has anything got to do with spiritual longing, I've always interpreted as a track about a working class couple trying to make ends meet.
I disagree.
The term ‘living on a prayer’ refers to faith. In this case, faith that love will keep the central protagonists together, no matter what. They are, by definition, searching for something. Similarly, the U2 song is about a search. In their case, they haven’t found it yet, whereas the characters in the Bon Jovi song have. And now they pray they can hold onto it:
"We've gotta hold on to what we've got
It doesn't make a difference if we make it or not
We got each other, and that's a lot for love
We'll give it a shot"