The shocking tale was revealed by the US State Department’s International Religious Freedom Report.
It claimed the two-year-old and his entire family were locked up for their religious beliefs.
Several other cases of North Koreans being killed for being Christian were also included in the report, including the firing squad execution of a woman and her grandchild in 2011.
Other believers faced "pigeon torture", where they were suspended with their hands tied behind their backs, unable to sit or stand for days on end.
One victim said: “It was the most painful of all tortures.
“It was so painful I felt it was better to die.”
Some were tortured with sleep deprivation including one woman in solitary confinement who was driven to suicide in 2020 after prison guards refused to let her sleep.
As many as 70,000 Christians have been imprisoned for their faith under the Kim Jong-un regime, of a possible population of 400,000.
The new publication said several North Korean Christians hid their faith from their children.
It cited the finding of one NGO, Open Doors USA (ODUSA), which said: “A Christian is never safe.
“Children are encouraged to tell their teachers about any sign of faith in their parents’ home.”
Another NGO, Korea Future, said children were taught in school about the “evil deeds” of Christian missionaries, including “ rape, blood-sucking, organ harvesting, murder, and espionage”.
The report said: “One defector told Korea Future the government published graphic novels in which Christians coaxed children into churches and took them to the basement to draw their blood.”
And while most of the cases of religious persecution documented by Korea Future targeted those practising shamanism, it was Christians who typically received the harshest punishments.
It’s because they’re perceived as a “hostile class” and a “serious threat to loyalty to the state” the report said.
Officially, North Korea guarantees its people religious freedom in its constitution and the regime highlights the churches it has built in Pyongyang as proof.
But the publication said these churches operated only as “showpieces for foreigners”.
It cited the testimony of one defector, who said people could be arrested for lingering too long outside the churches and listening to music from within, or even consistently driving past them.
Ray Cunningham, from Illinois, US, visited Chilgol Protestant Church in Pyongyang during a service.
He told Pen News: “I came away wondering just how real this is.
“Are the services regular? The church seems maintained but is it a regular event? You see no evidence of religious activity in the society – except for Buddhism.
“It feels real but like many things indeed it may be somewhat of a show for tourists. In this case, it might be a mixture of showmanship and a few elderly Christians in the area.”
He also noted something highlighted in the report – no children attend the services.
He added: “The congregation was made up of older men – all seemingly over 65 – and women over 40.