A group of Christians say Wales's national flag is "demonic" and should be changed.
The Welsh Christian Party claims the red dragon on the nation's standard is at odds with the country's position as a Christian nation.
It wants the flag to be replaced with the black and gold cross of St David.
Party leader the Rev George Hargreaves said a symbol of the devil should not "reign over Wales for another moment".
He said: "Wales is the only country in history to have a red dragon on its national flag.
"This is the very symbol of the devil described in the Book of Revelation 12:3. This is nothing less than the sign of Satan, the devil, Lucifer, that ancient serpent who deceived Adam and Eve in the Garden of Eden."
The party has launched an online petition calling for a referendum to allow the Welsh people to decide which flag they would prefer.
Historians and even fellow Christians said the symbol of the dragon had a "long tradition" in Wales and was a source of pride.
Welsh historian John Davies said: "It's been part of our tradition for more than 1,500 years. On the other hand the flag of St David has a much more specific remit."
He added: "When you see the Welsh flag you know what it is. It is recognisable in the same way the Union Jack or Stars and Stripes are. What is the point of changing it now?"
Bishop David Yeoman said few Christians in Wales would associate the dragon with the devil.
He said: "The dragon is a very ancient symbol in Wales. I doubt whether most Christians would see it as demonic. They see it as a symbol of the past."
Gregory Barker, acting head of the school of theology and religious studies at Trinity College, Carmarthen, said many Christian countries had flags without a specific religious symbol on them.
He added: "What's most important is that the flag is something the citizens of that country can endorse."