Article one describes the Manifestations' twofold station, one in essence and distinct in mission, and compares the concept to the Sufi Perfect Man and the Hindu avatar. A more specific and more consequential question article one does not address is what Baha'i teaching says about their reliability: can a Manifestation err, and if not, how far does that protection extend to the human institutions that come after them.
Baha'i doctrine attributes to the Manifestations themselves what is generally described as "Most Great Infallibility," an inherent freedom from error covering their teaching without qualification, grounded in their station as the source through which revelation comes rather than in any confirmation from outside. Abdu'l-Baha, as the appointed interpreter under the Covenant, and the Guardianship and Universal House of Justice that followed him, are instead held to possess a more limited, conferred infallibility, protecting their authoritative interpretations from doctrinal error within their defined sphere without claiming the Manifestations' unqualified status.
The distinction matters because it lets the Covenant do real work without collapsing every later Baha'i institution into a further Manifestation. A structurally similar problem, how far a founder's authority extends to later human interpreters acting in the founder's name, recurs across traditions, Catholic magisterial infallibility restricted to specific solemn conditions being the clearest parallel, and the Baha'i answer is to grade infallibility by station rather than extend or withhold it as one all-or-nothing attribute.