One argument for god follows the thread that because there are so many claims and evidence that god exists, it all fits together; the Cumulative case.
However, whether or not all the arguments and evidence fit together is not the issue. 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 sceptic’s concern is not about the jigsaw fitting together (internal coherence theory of truth) but does it describe reality (external validity or the Correspondence theory of truth).
A well-crafted story like The Godfather may have no plot holes, so it all fits together, yet it’s still fiction. ‘Harry Potter has a scar’ is a true statement within the story world (Coherence). But that doesn’t mean Harry Potter is a real person. (Correspondence).
‘Claim A must be true because it fits with claims B, C, D, and E, so the theist professes. But they need to realise that a non-believer may also reject B, C, D, E etc. Furthermore, they have yet to prove B, C, D or E.
What’s left is one unsupported claim tied together to another unsupported claim, and so on.
The cumulative argument fails because no amount of poor arguments leads to one good argument. Also, vague definitions, and flawed reasoning, can make a narrative appear to fit together as long as you don’t look too closely.
Beliefs are like that; they’re 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. Fitting them together poorly doesn’t mean the narrative is based on fact.
Objections to specific god claim from sceptics are often brushed aside with this appeal to coherence; it might be called the Franchise Defence. What’s going on here is that an entire worldview (Christian franchise) is used to reject a specific rebuttal against a specific claim within that franchise. (claim A is true because it fits with claims B, C etc). It’s dishonest debating because the individual claims are not addressed on their own merits.
Each claim should be assessed for how truthful it is in describing reality. (correspondence). How well individual claims fit together (coherence) is irrelevant to the broader claim, they all describe reality.
Coherence means the narrative or paradigm has been well thought out, but I’ve heard sceptics make the point that Theists worldviews often need to fit together better when you look closer. It all makes the argument or claim fall flat.