Final answer:
Voltaire mentioned Zoroaster among laudable believers in a higher power, recognizing the ethical contributions from Zoroastrianism rather than focusing on its specific religious details.
Step-by-step explanation:
Voltaire's mention of Zoroaster in his letter against atheism, despite potentially considering him an impostor like Jesus, Moses, and Muhammad, can be attributed to his acknowledgment and praise of individuals who believed in a higher power, irrespective of the specific religious framework they operated within.
Voltaire's focus was on the necessity of faith in a Creator God, and Zoroaster, as a prominent figure believing in Ahura Mazda and exemplifying the embodiment of wisdom and the constant struggle against evil, would be an apt example of this principle.
Moreover, Zoroaster's moral and ethical teachings echoed the developed ethical code that Voltaire saw as beneficial for society.
Thus, Voltaire could appreciate Zoroaster's role in fostering belief in a divine presence and moral conduct without necessarily endorsing the religious particulars of Zoroastrianism.