The advocacy group say that since July 2015, China has detained more than 230 human rights lawyers and activists; many of whom are Christian.
Christian lawyer Li Chunfu, who was recently released on bail, is showing signs of torture and a severe mental breakdown after his time incarcerated.
He was reportedly tortured with electric shock batons.
His wife told China Aid that her husband was left terrified by his ordeal.
"His eyes were lifeless," she said, "He clenched his fists all the time. [He] kept muttering "surveillance"... he felt like insects were biting his body inside, that his heart had been eaten away by bugs, and there wasn't much left."
Chunfu had represented 200 miners in Hebei province in a trial where workers were calling for better work conditions before he was placed in jail.
Andrew Boyd from Release international told Premier that China's Government needs to learn to recognise that Christians pose no threat to their leaders.
He said: "What they want to do is to serve their country well and these lawyers - who have used the law to stand up to the poor and needy don't oppose their country; they love their country.
"So Release's message is: stop the torture and let them go."
Boyd added that the treatment of Christians and other activists breaks human rights laws.
"When [the lawyers] are being rounded up they're being denied legal access, their families aren't being told where they are, they're being disappeared and being treated absolutely appallingly. China really must stop doing this."