However, early reports indicate that the storm has caused far less damage than feared. There have been no reports of deaths or serious injuries so far and the cities of Cairns and Townsville were largely spared.
The Anglican Church of Australia said its "thoughts and prayers continue to be with the people of Queensland" in the aftermath of the cyclone.
The Bush Church Aid Society of Australia already has an appeal in place for flood affected areas but is extending its assistance to include areas affected by Cyclone Yasi.
"While there have been no reports of deaths or serious injuries, Queensland has again been devastated," the ministry said on its website.
The humanitarian arm of Australian Christian Churches, formerly Assemblies of God Australia, is mobilising tens of thousands of volunteers through its churches in Queensland to help in the cities as well as the smaller rural areas it says have suffered "crippling" devastation.
ACC Relief International said in an update: "Rebuilding lives is a process that will take many difficult months and years."
Although Yasi has now been downgraded to a category 2 storm, heavy rains and storms are still blustering the region, causing flooding in the most northerly areas.
Around 175,000 homes are without power and there are reports of heavy damage to crops.
State premier Anna Bligh said: "It does seem Cairns has been spared the worst and that's a great relief. This has been, I think for many people, a terrifying experience but this morning because so many of them did take precautions, it seems that we certainly kept people safe in those centres and I'm very pleased about that."