The information isn’t very accurate, but that’s not your fault… and probably not the fault of the people who made those articles. There’s actually more to the story.
The Celtic cross consists of two images: the circle and the Christian cross. The circle represents the sun, and was originally the symbol that represented the nation of Ireland. Many people don’t know that Ireland’s first flag consisted of a golden sun upon a blue field. It later changed to a golden sun emerging from dark clouds during the reign of Brian Boru (representing Ireland emerging from the dark times of the Viking invasions).
The pre-Christian Irish placed much importance upon the sun in their belief system. So much so, that the ancient Romans were inclined to believe that the main god of the Irish was Apollo.
When Christianity and Saint Patrick arrived, the Cross was super imposed upon the sun symbol for two reasons. It symbolized Saint Patrick’s sermon to the Druids that “the sun they worship will some day cease to shine in the sky, but the light of Christ is a new sun which will never go out.” This was in reference to one of several prophecies recorded by the druids during the reign of King Connor MacNeesa at the time of Christ’s crucifixion. You see, the sun really did go out, (amongst other things) and it caused quite a stir amongst the population.
The Celtic cross also represents the dawning of a new era… the coming of Christianity… a new sun… or rather Son.
The stone crosses also replaced the old pagan stone monuments.
Back to flags for a second…
Ireland’s third national flag was the papal keys and tiara on a red background. For a time, Ireland was a Papal state.
Ireland’s fourth national flag was a gold harp on a blue field, which was created by Henry VIII, in an effort to replace the Vatican flag, during the reformation period.
Ireland’s fifth national flag was the banner of Phillip II of Spain together with the Crusader cross banner. Phillip had been offered the position of administrator and liaison of Ireland for the Vatican.
Ireland’s sixth national flag was the familiar golden harp on a green banner, which originated from the 1798 rebellion (due to a mix up in fabric die : gold and blue make green).
Ireland’s current tricolor flag originates from the 1916 rebellion and later war of independence.