>>I also believe that Perry doesn’t listen to Christian music and had no clue who they are. <<
Well, that’s where you’re wrong. Perry started out in Christian music, releasing an album as Katy Hudson.
That is what I had thought. As I recall, she is a P.K. (Preacher’s Kid). The song in question was from the general period when she would likely have been exposed to it. (I am not saying I entirely agree with these kinds of suits.)
Similarly, Joy Williams, of the erstwhile Civil Wars [Hunger Games soundtrack], started out in CCM (or whatever they call it now). I think she was the daughter of the man who operated the Mount Hermon retreat facility in the Santa Cruz Mountains. I never met her, but I knew someone from her class at Valley Christian High, where I think Williams graduated as Valedictorian.