Is 'The reason is because ...' redundant?

Question

[Source:] The phrase "the reason is" implies a causal relationship between two events or states. For example, the reason that the wagon is red is that I painted it with red paint.
I could also say the wagon is red because I painted it.
CAUSE: I painted. EFFECT: it [the wagon] is red.

So ... 3. “the reason is because,” ...
[=>] 4. The cause of there being a reason is that I painted it. ... 
[=] 5. “I painted the wagon and that is why it is red because I painted it.”

How does 3 => 4 => 5 ? Please show all steps and thought processes? I ask NOT about how, whether, or why this determiner phrase is claimed as redundant; I wish to justify its redundancy.

Afterword: Sorry for misleading, but I might've failed to ask my intended question. I was instead seeking an answer such as the following, from here, which user StoneyB kindly recommended:

In a similar vein, some claim that because because usually means something like “for the reason that”, you’re really saying “The reason is for the reason that”
when you say[:] the reason is because.

Answer 1

The construction The reason is because X has been upsetting pedants for about four generations now. Don't worry about it: it is a fixed phrase and beyond grammatical niggling. Millions of people use it every day, in every register, and writers of the very first rank have used it for at least four hundred years.

If you want a reasoned discussion from a recognized expert you may consult the blog Motivated Grammar written by Gabe Doyle of the Language and Cognition Lab at Stanford University:

A mild amount of redundancy improves the likelihood of the message being transmitted correctly. The problem is when there’s too much redundancy, slowing down the rate of communication. (A common problem in children’s conversations, for instance, or a boring person’s stories.) Using because instead of that here doesn’t slow anything down, though — aside from the couple hundred milliseconds the additional syllable might cost the speaker — so I’m pretty unsympathetic to this complaint as well.

But I beg you, abandon the effort to understand the use of words by replacing them with their etymologies and dictionary definitions. That's not how any language works; it's a dead end for a learner.

Answer 2

You cannot analyze a sentence in a natural language — any natural language — by syntactic substitution and rearrangement, the way you are trying to do. Natural languages do not work that way. Your "3 => 4 => 5" is not even wrong.

You are also proceeding from an incorrect assumption: the phrase "The reason is because" is not redundant. It can be shortened to "The reason is" without changing the meaning, but that doesn't mean the word "because" is redundant! It is just playing a non-semantic role.

So it's not redundant, so what is it doing? First, think about spoken language. All spoken languages have filler words, which have no semantics but convey "I'm not done talking, I need a little more time to think of how to say the next thing." There are generic filler words, such as "uh" and "um", that can be used anywhere, but native speakers will often use words that fit grammatically and don't add any semantics, instead. If someone said "the reason is because X" out loud, the because would be a filler word in that sense. Again, it's not redundant, it's said for its effect on the conversation rather than on the communication.

Now, in written language there is no need for filler, but there is a notion of rhythm and flow, and English permits a fair amount of flex in sentence structure for the sake of rhythm and flow. Here are two examples (from the document linked in StoneyB's answer) where because improves the flow of the sentence:

“If the fellow who wrote it seems to know more of my goings and comings than he could without complicity of mine, the reason is because he is a lovely old boy and quite took possession of me while I was in Boston”
[1915, Robert Frost]

“… one of the reasons why I am not particularly well read today is because I have spent so large a part of the last twenty years rereading Dickens and Jane Austen.”
[1932, Alexander Woollcott]

Sentence flow is a highly subjective thing which you have to learn by osmosis. Don't worry about it until you are able to read fiction in English for pleasure without a dictionary. Then read a lot of fiction in many different styles, and your ear for it will begin to develop.

Answer 3

It's not a question of redundancy; it's a question of correctness.

Consider this example:

Patient: I missed my appointment!
Doctor: What was the reason?

Some potential responses are:

1. The reason was the fact that I overslept.
2. The reason came about because I overslept.
3. The reason was because I overslept.

Now consider the meaning of each:

1. Sentence 1 implies the patient was either asleep at the time of his appointment, or it was otherwise impossible for him to make it in time (e.g. due to transportation delay)

2. Sentence 2 implies the reason was something else entirely, but the original cause was the fact that he overslept. For example, he might have overslept, his house might have caught fire when he was asleep, and he might have had to deal with that instead of coming to his appointment.

3. Sentence 3 actually means the same thing as sentence 2, but it's not obvious because the verb here is "was", and "was" is a passive verb -- it isn't in a position to receive the emphasis in this sentence. If you change "is" to "exists", you will see that the the meaning matches that of sentence 2.