The Baha'i community said that Hamed bin Haydara, who has been detained since 2013, will face an appeal hearing on Tuesday in the Huthi-controlled capital Sanaa.
The US State Department said it was "deeply concerned" that the Iranian-linked rebels have targeted dozens of Baha'is and voiced alarm over accounts that Haydara has endured "physical and psychological torture."
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"This persistent pattern of vilification, oppression and mistreatment by the Huthis of Baha'is in Yemen must end," State Department spokesperson Morgan Ortagus said in a statement.
The Baha'i community on Thursday released what it said was the response to Haydara's appeal, with the prosecutor accusing the faith of being founded on "satanic thought."
It said that Haydara has also been accused of seeking to create a separate Baha'i homeland on the Yemeni island of Socotra.
"The prosecutor's arguments do not address the merits of Mr Haydara's appeal and instead make absurd, wide-ranging accusations that are not based in law or in fact," said Bani Dugal, principal representative of the Baha'i International Community to the United Nations.
He charged that the prosecutor was following the tactics of Iran's clerical regime, which allows freedom of religion to several minorities but targets the Bahai's, whose founder the Baha'u'llah was Iranian born in 1817.
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The Baha'i faith calls for unity among religions and equality between men and women.
Baha'is consider the Baha'u'llah to be a prophet, a sharp contrast from the orthodox Islamic view that Mohammed was God's final messenger.
The Huthis control vast swathes of Yemen despite a US-backed military campaign led by Saudi Arabia, which has contributed to what the United Nations calls the world's worst humanitarian crisis.
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