Oppression and discrimination towards Christians has only worsened during the pandemic, says Release International.
The charity, which supports persecuted Christians, said many had been denied food and relief aid by governments and NGOs because of their faith.
Some countries have escalated their crackdowns on Christians.
This is the case in China, where there were reports of Christians being arrested for meeting online to worship and pray during lockdown.
Authorities have "totally prohibited" online church services and prayer meetings, Release partners in China said.
"Nothing constituting a religious service is allowed," they said.
They believe the Chinese Government is exploiting Covid-19 to increase its long-running crackdown on Christians.
"They have accelerated campaigns such as the forced demolition of crosses against even government-sanctioned churches," the partners said.
"Pastors have been rounded up for sharing the gospel and distributing facemasks on the street."
In many countries, Christians have experienced crippling poverty during the pandemic.
In Algeria, there is no social security or government support, leaving many Christians struggling to get by.
A Release partner in Algeria said: "Many Christian families have had to stop work because of the lockdown and have lost their income. They have been rejected by society and their families as a result of their faith. The demand is huge."
In Pakistan, the situation has been especially difficult for converts from a Muslim background because the only form of financial support comes from families. Muslim families often withdraw this support to family members who convert to a different faith, Release said.
"These individuals have been rejected by society and their families as a result of their faith," said Release's Pakistan partners.
Just buying food and paying the rent has become a huge challenge for many impoverished Christians, let alone buying face masks and hand sanitiser.
"The government is not able to support Christians in the villages, slums or brick kilns," the partners said.
In Upper Egypt, there have been reports of Christians being refused food and support from organisations distributing aid.
Release partners report: "The authorities are helping Muslims but not Christians. And churches that try to help are being closed by police order."
Release partners are distributing aid packages to Christians in Algeria, Ethiopia, Egypt, Nigeria, Pakistan and Turkey.
It has launched an appeal to support more Christians during Covid-19.
Release International CEO Paul Robinson said: "Covid-19 is having a devastating impact on the lives of many poor Christians. In places hostile to the faith Christians are experiencing increased hardship.
"Food is now in short supply. They are unable to work and can't earn, and support is being withheld because of their faith.
"Their cries for help are being ignored by local charities who are distributing food packages only to families of other faiths. We can't afford to delay. These Christians need our help."