no laughing matter

I just read a joke online.
It had an elaborate set up around Jesus not having a last name.
I didn't understand the punchline.  The joke was based on the joke teller's opinion of the Immaculate Conception.  A word of warning for comedians if you are going to make fun of an entire religion the least you can do is to know what you are talking about.  Don't take on big concepts, just don't do it.  When you omit facts it's no longer humor it's tragedy.. It would be funny if the person who thought a religious belief was stupid realized they didn't grasp the concept after posting it online.