Even if there is no God, there is an ethical imperative to treat all other people known and unknown as equally valuable as ourselves as created by our mutual creator, whether you give that a name or just see it as the unknown forces or principles creating and shaping our universe.
"God" for me is a easier word for "the unknown forces or principles creating and shaping our universe". It is not unreasonable to believe that as my thoughts shape my emotions and movements and other people's reactions to me, and other people's reactions to them, my prayers or thoughts may have effects beyond the rationally predictable (limited by our limited knowledge of reality).
As i understand it, Catholics don't actually pray to saints like they were gods or demigods, but to use them as a focussing aid, like imagining a good friend with you, or humming Ohm, to communicate with what you can of the principles behind your ongoing creation.
How can there be miracles, when bad things happen? This is quibbling about detail. I've never met anyone, no matter how clever, who has built a better universe than this one, with all it's earthquakes and cancers and wars and whatever. I don't understand the fine tuned balance of where we are in the quantum creation of time and space and matter and energy, so I see all of existence as miraculous.
Lovely moment in today's smh, next to the headline "Rudd: I believe in miracles", a photo of three political adversaries, Barnaby Joyce straightening Kevin Rudd's jacket, while Julie Bishop oversees this intimate adjustment.
Focussing on where the glass is half empty may give keener detail, but make you feel thirstier. Looking on it as half full gives greater happiness. As always, the choice is yours ;)