I went hunting for references to God in national constitutions. There are lots, at least half of Europe. There is a debate on now whether God should be mentioned in the European Union constition. From a Warsaw paper:
Let's now talk about the vital yet delicate problem of Invocatio Dei [reference to God] in the preamble to the future European constitution. What is the Polish stance?Our stance has been pretty clear. We agree that Christianity is an important determinant of Europe but this doesn't mean it was necessary to accept Christian values as a foundation of Europe without due consideration. When ancient Rome, ancient Greece and the Enlightenment was mentioned in the draft preamble, I had no doubt that Christianity should be there too. Not from the point of view of religiousness but from the point of the role of Christianity in the creation of European civilization. According to such reasoning, there was no reason why Christianity could not be put down in the Constitution. Instead, the whole paragraph on the cultural and civilizational heritage of Europe was omitted. And when the discussion about including Christianity as a religion began, the problem of Judaism, which is one of the roots of Christianity, and Islam, which has been present in Europe for 700 years, could not be ignored. This, in turn, created various additional problems, for example the issue of the possible membership of Turkey in the future.
The introduction "in the name of God Almighty," which was proposed by many Polish politicians, the Polish Episcopate and the Vatican, was out of the question. Today's Europe-and that was clearly seen during the debate-considers itself secular, whereas the issues of creed are treated as a private matter in most European societies. Invocatio Dei would therefore be unacceptable to atheists.
In this situation, I think the current entry is the best solution-it is one sentence long and refers to common traditions, cultures and religions in the plural, without being more specific.
In my opinion, the over-sensitivity in Poland, Spain and to a lesser extent in Italy, was the result of the thesis that the EU is "Godless". It was one of the crucial arguments among euroskeptics, also in Poland: if it's Godless, then we must force it to say something about God in its major document. Meanwhile, this thesis is absolutely false-the EU is not Godless, the EU has simply regulated issues of religion and faith so that citizens of all member states can enjoy full freedom, and spiritual life is not confused with the work of the European Community.