was race or religion the unique feature of western civilization?

At no other time in history - other than in the 7th century when Rome chose it as the bastion of Christianity in the face of rising Islam - has Ireland played any major role in shaping the political, economic or cultural evolution of the western world. Indeed, the universal state of western civilization was represented by the Hapsburg Monarchy 1526-1918, not the Celtic kings.

And, except for continuing to lead the Catholic Church, the political power of the Pope in Rome has diminished considerably in modern times.

If Christianity - in particular Catholicism - were the unique feature of Western civilization at its inception in 675 in Ireland, then it did not remain so forever.

However, Ireland cannot be discounted for another major unique feature of Western civilization at its inception in 675 that has remained strong - it's white Celtic ethnic identity.

Because of the abominable conditions of overpopulation and poverty in Ireland, the Irish provided by far the most immigrants to the new worlds in centuries to follow. In that respect, the Irish Celts most certainly played the most important part in shaping the ethnic identity of the evolving western civilization.

In that respect, Ireland in 675 was indeed the 'cradle' of western civilization. If historians believe that a unique ethnicity founded western civilization, then it was a white Irish Celtic ethnicity - not the Mediterranean ethnicity of the Romans, French and Spanish, nor the polyglot ethnicity of the various other northern tribes in the western world at the time.

In fact, because three separate and distinctive Christian civilizations evolved in Turkey, Russia and Europe - respectively represented by the Ottoman Empire, the Muscovite Empire and the Hapsburg Monarchy - indicates that Christianity was not a unique feature of western civilization.

Of race and religion, then, race in the form of white Celtic ethnicity, was the unique feature of Western civilization.