Editor
Tish Davidson said:
Thanks, an editor tried to tell me today that sentence #1 needed a comma because "because" should be treated like a coordinating conjunction (and, or) and needed a comma if it was followed by a complete sentence (I need to ...cake). That didn't seem right to me. I suppose that's why editors hire copyeditors.
Unfortunately, a great many editors have no copyeditor to fall back on. This is pretty basic stuff any editor should know, and it's a little frightening that you've found one who doesn't know it.
It's rarely possible to judge where a comma should go by whether or not the speaker would pause in a given spot, but this is one time where it works well. The editor should say the sentence aloud. Or have someone say it to him. There is no pause.
It really might help if the editor turned the sentence around and made a comma necessary. "Because I need flour to bake your birthday cake, I am going to the store."
"Because" must be joined to one independent clause or the other, and no matter which you choose, you lose an independent clause. "I am going to the store because," is not an independent clause, and ",because I need flour to bake your birthday cake" is not an independent clause.
The only way to avoid this would be to place a comma before and after "because," which makes no sense at all.
There's even a "because clause" rule. "The only time a "because clause" should be set off with a comma is if the meaning of the sentence will be misunderstood without the comma."
The only example of this I could find on the web was :
"I knew that President Nixon would resign that morning, because my sister-in-law worked in the White House and she called me with the news."
Without that comma, many might read the sentence to say that Nixon's resignation was the fault of my sister-in-law. Though I doubt I'd use a comma in this sentence. The meaning seems clear enough to me.
But if "because" is essential to the meaning of the first independent clause, or if it explains the first independent clause, and the sentence is readily understood, then the "because clause" rule should always be followed.
In other words, as long as the meaning of the sentence is clear, no comma should be ever used before a "because clause."