Open Doors says it is one of the few groups left in the country helping those who cannot leave.
Lisa Pearce, Chief Executive for Open Doors UK and Ireland, told Premier: "These people are too poor flee or too infirm to travel.
"The Church has traditionally cared for the needy and the infirm, we are simply carrying on our work, helping people of all denominations left behind, struggling to survive."
Aid is distributed by pastors who could have chosen to leave but have instead decided to stay and help.
Pastor Edward of the Alliance Church in Damascus, said, "The relief work is going on full power; the need is still growing in the city.
"Every few months, new waves of internally displaced arrive in the capital."
Lisa Pearce told Premier that: "We're trying to get Christians specifically to be praying for the Churches that are still in Syria - and also provide practical help and funds that will allow us to provide food, provide medicies and provide trauma counselling amongst other things - the basics of life."
She added: "Now, more than ever we need to step up our help and provide them with safe, secure accommodation and food.
"Open Doors is completely dependent on the generosity of individual people and church congregations - it does not receive any government aid.
"We want to be able to give them more help and we also want Governments to ensure that there is a safe area for them to stay in.
"They cannot move."
Listen to Premier's Hannah Tooley speak to Lisa Pearson here:
