I suggested something similar but your sample size is too small, if someone tossed a coin 1000 times without praying a single time and then did the same while praying to get the results they want we are going to find out there is not a statistical meaningful difference between the two samples, which leads us to a very simple conclusion, praying has no effect on our probabilities, something that should be obvious without running this experiment but this can be done just to make sure this is the case.
It can't be done actually because how are you going to verify that the person actually prayed? What does praying even mean? Talk some bible verses? This experiment can't be done, but I guess most of us agree that calling for some transcendental power for your own good does not work out very often...
