When questioned by reporters, Ms. Asa at first brushed off the allegations, calling them a “private matter” and saying she had little recollection of the Facebook account from which she had apparently lifted one of her most famous posts to the social network. Two days later she acknowledged in a Facebook post that she had plagiarized, writing, “We all have. Who hasn’t done that?”

Hard-line Islamist websites seized on the news. The Islamic Defender’s Front, a hard-line organization that campaigned to have Mr. Basuki, the former governor, arrested on blasphemy charges, said in a Facebook post that Ms. Asa and the governor shared similar faults.

“It’s exactly like Ahok who won’t ever admit he’s wrong,” the post said, referring to Mr. Basuki by his nickname.

A Facebook account bearing the name Mita Handayani, which Ms. Asa had been accused of plagiarizing from, said on social media that she had no problem with Ms. Asa’s using her writing. Ms. Mita added that she thought Ms. Asa was merely being targeted for her religious tolerance.

The lightning rise and potential fall of the East Javanese teenager has led Indonesians to reflect on why they had elevated a small-town high school student to the status of national hero so quickly. And it ignited an online debate in Indonesia about how serious the offense of plagiarism was, and whether it should be forgiven.

Pradewi Tri Chatami, 30, a recent college graduate, posted on Facebook that the recent triumph of hard-line Islamic groups in Jakarta meant that progressive Indonesians were looking for anyone willing to stand up for pluralism.

“It’s a scramble to find an icon,” Ms. Pradewi said in a telephone interview. “I liked her because she was a sophisticated young woman who was brave enough to share her thoughts. But to idolize someone is ultimately to sacrifice them.”