Two Christian aid groups were recently suspended from Afghanistan over claims that workers were proselytizing.
The offense carries the death penalty and now, the accusations are sparking protests from Muslims in the country.
Wednesday, anti-Christian protesters took to the streets in Afghanistan for the third time since the government suspended the groups.
College students in the northern city of Mazar-e-Sharif shouted anti-American slogans and defended Afghanistan's ban on religious conversions.
"We want those who have converted from Islam to be punished," protestor Zabiullah Khan said. "We also want the Islamic Republic of Afghanistan to ban all the churches that have been established and any organization spreading Christianity here."
The demonstrators shouted death threats toward foreigners who try to convert Muslims. Proselytizing is illegal in Afghanistan and many other Muslim countries.
The Afghan government has launched an investigation of the two charities. Both groups deny the accusations, which came after photos of Afghans worshipping and getting baptized were posted on the Internet. The photos have not been directly linked to the groups.
The Church World Service and Norwegian Church Aid groups have been involved in Afghanistan for the past 30 years, working to improve agriculture, education and general living conditions.
Protest leaders demanded both organizations be shut down and their foreign employees brought to justice.