Saw it last weekend. I quite liked it. Not the best, but not "Doom" or "Skull" either which is a positive to me.
The only problem I had with it - other than the wonky CGI pull-back of the train as Indy is beginning his run on the roof - was the sound mix. To me, it was like "Spider-Man...
Maybe Indy is differentiating between "magic", a form of showmanship, and the "supernatural", an otherworldly power.
I don't know. Just making up an excuse until we see the context of the dialog.