The group arrived home earlier today amid controversy over their release, including allegations that the South Korean government paid a ransom to free them.
Carrying portraits of their two colleagues executed by the Taliban, the former hostages looked tired as they faced television cameras upon their arrival at South Korea's Incheon airport.
One of the 19, Yu Kyeong-sik, said they owe their compatriots an enormous debt.
"We went to Afghanistan to practice sharing love," Yu said. "However, we were kidnapped accidentally, and caused the whole country to worry. We also apologize to the government."
The 19 former hostages were released following face-to-face meetings between South Korean officials and Taliban militants.
They were the last of a group of 23 South Koreans kidnapped in Ghazni Province on July 19.
The captors killed two of the hostages, Presbyterian pastor Bae Hyung-kyu and medical-services volunteer Shim Sung-min, in the initial weeks of the standoff.
Two sick hostages, both women, were released in mid-August in what the hostage takers described as a gesture of "goodwill."
The group had traveled to Afghanistan against government advice.
Korean media and some foreigners based in Afghanistan criticized the South Koreans for a lack of care and preparation before traveling to the country, where a violent insurgency continues against the UN-backed government installed after the U.S.-led ouster of the Taliban regime.
Afghan Interior Ministry spokesman Zemari Bashari was quoted as saying the day after the kidnapping that the South Koreans were "very carelessly traveling in a chartered bus."
Bae Shin-kyu, brother of the slain pastor, appeared with the former hostages today. "As a family member of the hostages' leader, I'm very sorry for causing trouble for our fellow citizens," he said.
The former hostages were reunited with family members as they had medical checks after leaving the airport.
The representative of the hostages' families, Cha Sung-min, made a statement.
"We've been going through such a hard time, but thank you all for encouraging us," Cha said. "We promise to return all the love that we got from you."
South Korean citizens welcomed the return of their compatriots. One of them, Shin Dong-in, said Seoul did a "good job."
"There may be some criticism from the international society, but still, a person's life is most important," Shin said. "The South Korean government did a good job, although to prevent repetitions, I think a clear line should be made on the right demand compensation."
Taliban representatives have been quoted as saying the South Korean government paid $20 million. But other Taliban sources said no ransom was paid. Afghan officials have said a sum slightly under $1 million was handed over.
South Korea, which has come under criticism for negotiating with the kidnappers, has denied the claims. Seoul said it agreed to pull its troops out of Afghanistan as previously scheduled by the end of the year, and discourage missionaries traveling to Afghanistan.
Afghan Foreign Minister Rangin Dadfar Spanta has said it was lamentable that it appears South Korea heeded a Taliban ultimatum to secure the hostages' release.
The Afghan government was sharply criticized after it exchanged five Taliban prisoners for a captive Italian journalist in mid-March. The captors' execution of two Afghan men who were abducted alongside the Italian compounded the government's dilemma.
Officials in Kabul have repeatedly pledged that they would not repeat such a deal. Spanta warned that meeting hostage takers' demands threatened to allow Taliban fighters to operate a hostage "industry."
Their church has insisted the 23 Christians were doing aid work and were not involved in missionary activities.
Conversion from Islam or seeking to convert Muslims is regarded as a serious offense in the Islamic Republic of Afghanistan.
Members of a South Korean Christian aid group that tried to organize a three-day "peace festival" in Afghanistan in August 2006 were expelled after Islamic clerics accused them of trying to convert Muslims to Christianity.
(compiled from wire reports)