for fuck's sake (ffs)
you have got to be fucking kidding me
Fornicating Black Holes and Pulsars!!
"TANSTAAFL!!! There Ain't No Such Thing As A Free Lunch" Robert Heinlein, "The Moon is a Harsh Mistress".
TANJ There Ain't No Justice, Larry Niven, Somewhere, I think, in "Tales of Known Space."
I would say, don't sweat it. Just use what you use - and I say that for a few reasons...
Oh My Gawed!
Oh for doG sakes!
Kryspy Kreme's nailed to a cross!
Mary mother of Joseph's bastard!
Holey cow! (leaking milk)
Holey Scripture! (full of holes)
Holey Nipple Twister, Batman!
The traditional cultural 'swear words' should remain the same or change as the opportunity for change arises. In many cultures, derogatory words that are the equivalent of swearing in English arise based on unfavorable descriptions of acts, attitudes, objects, or especially sexual organs. For example, in Thai, there is a childish swear word ("eup") to describe sexual coitus (and literally, a childish word: a child would use this word to describe two dogs having sex in the street, for example), there is a grammatical description of using sex to get ahead ("chai dtao dtai" instead of "chai dtai dtao", or roughly translated: "using your tits to get ahead" instead of "getting ahead by your hard work"), many objects, especially fish and mollusks, are used as sexual euphemisms (such as the word for 'oyster' being synonymous with the word for vagina, to the extent that, in intimate conversation, saying you want oyster sauce can prompt the question: "what kind?"), and my last two examples- and personal favorites- are the words "Ka-Ji-aow" (meaning, literally, "Little boy penis") and "Ma-kheua-phaow" (technically a breed of long green egg plant: in euphemism, an old man's penis that can no longer achieve an erection).
It's been my experience in many languages that acts done privately or which otherwise have the potential for embarrassment, or otherwise words that insult lineage or the outcome of your family, are the basis for most words of this genre. Even words in English like "damn" describe an unfavorable outcome (damnation). So with this in mind, I'd bypass the search for religious contexts to put atheist insults into altogether and, in the spirit of this topic, go for the balls.
By the four balls of Jesus, Mary and Joseph.
"Jesus FUCKING Christ" usually provokes a salutary response aswell.