I am editing answer explanations for a school curriculum. The more I read the phrase "because although", the more stumped I become on whether there should be a comma between because and although. Here's a basic example:
After a short reading passage, a question asks for the main idea and then gives multiple choice answers. Let's say Choice A is "The narrator hates lemons." The answer explanation then reads:
"Choice A is incorrect because although the narrator does say she hates lemons, this is not the main idea of the passage."
I've been putting a comma ("because, although the narrator does say she hates lemons, this is not the main idea...") because I regard that phrase as parenthetical and unnecessary. Without it, the explanation would read, "Choice A is incorrect because this is not the main idea of the passage." The antecedent for this is in the answer choice. The use of although is more of a concession to the student who misinterpreted the passage (Yes, it does talk about lemons, but that's not the main idea).
So... comma or no comma?
These are read by middle school and high school students and their teachers.