"All the faith he had had had had no effect on the outcome of his life" is it correct

"All the faith he had had had had no effect on the outcome of his life."

Is this a grammatically correct sentence?

Solution 1:

Grammatically correct from what I can tell, but stylistically ugly.

Some hads can be replaced by words which would hold the same or similar meaning in this context. By substitution, we can see the intended sense of the sentence more easily:

"All the faith he had had had had no effect on the outcome of his life."

becomes with a "once"

"All the faith he once had had had no effect on the outcome of his life."

and so on,

"All the faith he had once had ended having no effect on the outcome of his life."

I think the perceived need for such constructs comes about due to a sense of governing tense in a paragraph. But I most often see past perfect sentences lead a paragraph, to be followed by simple past. This seems acceptable, and from a practical point of view, is clear enough and easy to understand.

I once had a dog. His coat was green. He had a penchant for bones.

Compare it too:

I once had a dog. His coat was once green. He once had a penchant for bones.

The understanding of an historical dog is already in play, so adding 'once' in fact ambiguates things. Similarly, the mess of the had had had had in the sentence above can be cleared up by a change of style.

"All the faith he once had had had no effect on the outcome of his life."

is not meaningfully different from

All the faith he once had held had rendered no effect on the outcome of his life."

and is not significantly different in meaning from

All the faith he once held [had or "ended up having"] no effect on the outcome of his life."

Solution 2:

A comma would help make it more readable:

All the faith he had had, had had no effect on the outcome of his life.

As this website says, in Para. 5.A.4:

Use commas to separate words repeated within a sentence to avoid confusion.
Whatever that is here that smells, smells just awful!
What she does, she does well.
She came in, in tears.

Solution 3:

It is correct. The two hads have different grammatical roles. The first one is a modifier and the second is the main verb in the sentence. Here is a sentence that is similarly constructed. "All of the clothes he owned made no effect on his overall appearance."