there's no way of proving which one did it since you prayed to both. if you pray to one then a week later to the other maybe. it comes down to faith and i don't want to start a fight, but Lucifer is a fallen angel who tempts people, god has mood swings just look at the old testament vs the new. granted lucifer was pulling the strings sometimes but god could be rather spiteful himself. i like to look at Job [pronounced jobe] as an example of this. he was a religious man who worshiped god and was the most loyal follower you could imagine, he had the perfect life, he was wealthy with a loving family, lots of land, and every luxury imaginable. lucifer told god that Job wouldn't be so praising if he wasn't so happy. so god took EVERYTHING away, he killed Job's family, took away his wealth, and destroyed his home in one swoop. despite this Job never cursed god, but himself for letting it happen.
as i said, it's faith, worship who you think is worthy.