It is interesting that it took this long for this massacre to be confirmed:
This photo, released on Wednesday by South Korea’s Truth and Reconciliation Commission, shows the cemetery of Christians who were massacred by North Korean soldiers at Byeongchon Holiness Church in Nonsan, South Chungcheong Province.
Dozens of Christians were tortured and killed en masse at a church in Nonsan by communist soldiers during the Korean War, South Korea’s Truth and Reconciliation Commission said Wednesday.
After two years of investigation into the case, the commission confirmed that 54 Christians, including 29 minors, were murdered for their faith at Byeongchon Holiness Church by communists between July and September 1950.
After taking control of the city in South Chungcheong Province in July, within just one month after their invasion on June 25, 1950, North Korean soldiers initially tortured and killed three leading figures at the church.
But just before retreating from the region, following the successful U.N. Command mission at the Battle of Incheon, North Korean soldiers massacred the remaining church members and their families in late September, the investigation concluded. Thirty of the victims were women.
Korea Times
You can read more at the link, but the article says that over 1,700 Christians in total were executed during the war and many of them by communist sympathizers in South Korea that allied with North Korea.