"In the name of the Clave, [...] I ask entry to this holy place. In the name of the Battle That Never Ends, I ask the use of your weapons. And in the name of the Angel Raziel, I ask your blessings on my mission against the darkness." (14.10)
Okay, this isn't quite the Our Father, but it totally sounds like a prayer, Shadowhunter-style.
"When I saw [my father] lying dead in a pool of his own blood, I knew then that I hadn't stopped believing in God. I'd just stopped believing God cared. There might be a God, Clary, and there might not, but I don't think it matters. Either way, we're on our own." (14.43)
Jace has had a lot of tragedies befall him that have been totally out of his control, like the death of his father. So his reaction—that God is callous—is more than understandable. Either way, the God he's talking about doesn't seem all that interested in worldly affairs, the way the supernatural beings like demons and angels do in the book.