English

The sentence is grammatical, but it makes me stumble.

I'd say, "which belief leads etc."

or more pedantically, "and believing this leads etc."

or, "and this belief leads etc."

You could also think about skipping the second believing altogether. Since "flaws" is plural and "leads" is singular, there would be no doubt as to what "which"

Anonymoushave no flaws, believing which leads

I'd change it:

... have no flaws, a belief which leads ...

CJ

I like it.

I would agree that it needs to be changed. Consider:

1. X is the case, believing which leads to many problems.

In other words,

2. Believing that | X is the case | leads to many problems.

Thus the original sentence, as it stands, means:

2. Believing that | in Death of a Salesman ***** Loman mistakenly believes that his sons have no flaws | leads to many

Another case where everyone agrees.