The argument follows: there are so many arguments for God, and in the eyes of the theists, all the claims fit together; therefore, it must be true.
Cumulative claims are not the issue, however. The cumulative case is sometimes used to refute specific claims. It’s a problem because it does not answer the sceptic’s question.
You might call it the Franchise Defence. What’s going on here is an entire worldview (Christian franchise) is used to reject a single specific rebuttal. It’s dishonest debating because the individual claims are not addressed on their own merits.
‘Claim A must be true because it fits with claims B, C, D, and E. Theists don’t realise that a non-believer may also reject B, C, D, E etc. Furthermore, they haven’t proven B, C, D or E yet.
Coherentism is the truth that fits together, yet fiction can do that. A well-crafted story like The Godfather is still fiction, even though stories may be based upon real places.
The question is not how well the jigsaw fits together, (internal coherence), but does it describe reality (external validity)?
‘Harry Potter has a scar’ is a true statement within the story world. But that doesn’t mean Harry Potter is a real person.
Think of it as assembling a jigsaw puzzle; if the pieces don’t fit, you get a knife and cut them until they do.
Then sitting back, amazed that it all fits together.
Beliefs are like that; they are adjusted and tweaked so that the pieces fit together in the believer’s mind. Any discrepancies are either brushed aside, or meanings are altered, so it does make sense.
Vague definitions, and flawed reasoning, can make a narrative fit together as long as you don’t look too closely.
Coherence still doesn’t provide proof when all the claims are metaphysical and impossible to examine and test. What’s left is one unsupported claim to support another unsupported, and so on.
What is mistaken here is the difference between the Coherence and Correspondence ideas of truth. Yet many apologists think that just because a narrative or theory fits together, it coheres; it must therefore be correspondingly accurate.
That doesn’t follow.
The cumulative argument fails because no amount of poor arguments is enough. Fitting them together doesn’t mean the narrative is based upon fact.