Release International is warning of a likely increase in attacks on Christians across Afghanistan and the region after the Taliban's rapid takeover of the country following the US and Nato troop withdrawal.
The speed with which the Taliban re-took control of the country has shocked the international community.
While the Taliban has asked for a peaceful transfer of power, Release International says the dramatic turn of events will only embolden extremist activity.
One church leader in Afghanistan told the charity that Christians there are living in great fear. They include some Christians who worked for the government and are now at risk of reprisals.
Release warned that anyone identified as a Christian could be killed for their faith, and that they risk betrayal or falling victim to an honour killing by their own family members.
One Christian contact told Release that the situation there is "dire".
"Our brothers and sisters in Christ are telling us how afraid they are," they said.
"In the areas that the Taliban now control girls are not allowed to go to school and women are not allowed to leave their homes without a male companion."
According to Release, persecution against Christians was already increasing even before the Taliban takeover, with the church forced underground due to stringent apostasy laws which make converting from Islam punishable by death or imprisonment.
In the past, foreign Christian workers have been killed. Others have left the country.
Tragically, Release said many Christians are poor and so cannot afford to flee.
"They will be left behind," it said.
Paul Robinson, Release CEO, is asking Christians to pray for Afghanistan.
"The Taliban's swift advance can only embolden extremists," he said.
While thousands of Afghans, including many Christians, are streaming into neighbouring Pakistan, Release warns of dangers there too as the Taliban has been growing in influence in the country.
Pakistan's Taliban notoriously shot 15-year-old Malala Yousafzai for going to school. She survived and is now a human rights activist.
She says she is "deeply worried about women and minorities" in Afghanistan now that the Taliban are back in charge.
Release partners fear that the takeover in Afghanistan may destabilise north-western Pakistan.
"Pakistan especially may be impacted by the new mood of militancy – which will be bad news for Christians across the region," said Mr Robinson.
Release is working with partners in the region to provide Christian radio broadcasts in the Dari and Pashtun languages. They are also producing Christian literature and digital discipleship material.
Their partners are calling for prayer.
"Into this darkness, our ministry is bringing a daily message of hope, life and comfort," they said.
Mr Robinson called the radio ministry the "one real ray of hope".
"Radio can be picked up everywhere – including in Pakistan, where many of the Christians are seeking refuge. The same is true of social media," he said.
The charity sees further hope for spreading the Gospel in advancements with internet and women's education in recent years.
"In places like Afghanistan the church has had to learn to operate much as the early Church in the Book of Acts – under continual threat of persecution. But today the church is better resourced and equipped to handle that challenge than ever before," he said.
