My kids have heard the F word. They are aware it is offensive to some but not all. They feel no need to use it.
Alright, I've given you two hard Warnings and I don't know how many informal cautions about getting too personal / crossing the line between post and poster. Time for another hard Warning, it seems. Comments to PM (Conversations).
Now, see, the N word is different. There is a history and context to it about specific ways it has been used to demean other human beings. That word has a power given to it by history. Other "standard" curse words do not. And as for F-bombs? My child's corporate accountant mother curses like a sailor and has been dropping F-bombs around her for her whole life. Hasn't damaged her a bit.
And yet it featured very scantily clad women, a crew that was of both mixed race and sex, the first interracial kiss on TV between a Caucasian and an African and, yes, swearing. It all seems so child-friendly now, but that certainly wasn't the intent at the time. Exactly the opposite was the case.
While I know many Catholics who do believe this most of the Christians that I know do not. I think that's a broadbrushed stereotype that unfortunately, as you note, is perpetuated by people in power within the religious structures. Thankfully, I have had many pastors and leaders who do not hold to that belief.
That would only explain the people who've also had a problem with "Let's get the hell out of here." and "Haven't you got any goddamn feelings about that?" Indeed, one would think devout Christians would more likely take take offense to invoking God's name in vain than to anything carnal. But in my experience, most people who regularly complain about the usage of "fuck" specifically in Star Trek seem to have no problem with the former and would usually go on lengthy spiels about how "goddamn", "hell", "shit" etc. represent a much milder language than the dreaded f-word which is somehow a watershed of uncivilized, barbaric behavior, bad quality and a lack of creativity. A word that is completely inappropriate for a TV-show that is supposed to be "child-accessible" yet is at the same time constantly derided as something only young kids trying to sound adult would ever say. Only "fuck" ever receives that treatment, including the oft-invoked need for justifying its legitimate story purpose. Everything else is a creative choice, but for some reason "fuck" isn't.
Fuck that
