You also have declining populations in Europe. It may that that people from the Southern hemisphere will come to Europe and re evangelize the culture as most from the South are religious, devout.
There is an interesting article from George Weigel in which he shows the difference between the American Church and the European Churches:
There are some explanations for the decline of the Church in Europe, this following blog agrees with an article in the Economist:
…that says factors such as the resurgence of Catholic activism in countries like Spain to combat a hyper-leftist secularist government’s social agenda, the varying nature of the official links between the state and the Catholic Church in different European countries, and the widespread disgust at the utterly inadequate response of so many European Catholic bishops to the sexual abuse problem. But there are other factors:
In the heady days after Vatican II, however, large numbers of West European Catholic bishops, clergy, theologians and laity really believed that the 1960s progressivist agenda was the future. Unfortunately, like all forms of liberal Christianity, “progressivist” Catholicism carried the seeds of its own destruction. Sociologically-speaking, it’s hard to deny that those forms of Christianity that (a) demand nothing from its adherents in terms of belief beyond an emphasis on tolerance, diversity, and endless dialogue-for-the-sake-of-dialogue; (b) dilute dogma and doctrine to the point of meaninglessness; © that become yet another means of self-affirmation in a culture full of self-affirmation; (d) embrace post-1960s sexual morality; (e) essentially anathematize anyone who doesn’t more-or-less adhere to secular left-liberal political, social, and economic positions, eventually self-destruct.
The reason is simple: no-one needs to be a Christian to hold these views. The actual content of orthodox Christianity is, in fact, opposed to all these positions. Hence, no-one should be surprised that most who embrace these views sooner or later eventually marginalize their Christianity to the point of irrelevance to their daily lives or simply drift away altogether. The odds of them raising their children – assuming they actually have any – in the Christian faith are remote at best.
Of course, the documents of Vatican II provided no warrant for Catholics to follow such a path (that’s why the dwindling band of progressivists talks endlessly about “the spirit” of Vatican II). Yet that didn’t deter a good number of West European Catholics from doing so. Today, we are witnessing the fruits of such choices throughout much of Europe. Everywhere the “liberal” agenda was adopted, a collapse in Christian belief and practice has been the result. It is hard to find exceptions to that rule.
The first is the impact of urbanization in continental Europe from the 1950s onwards. As the current archbishop of Paris, Cardinal Andre Vingt-Trois, observes in his excellent book, Une mission de liberté (2010), Catholicism was woven into the very fabric of rural France (and other traditionally Catholic rural areas in Europe). With the mass shift of population to urban areas after World War II, that world came to an end, and, with it, a type of mass Catholicism. The Church struggled to adapt to this population shift. Some of its attempts to do so – like the “worker-priest” experiments of the 1950s – were an abject failure and ended with flirtations with the dead-end of Marxism.
The second is the impact of the church-tax in countries such as Germany and Austria. While it permits the Catholic Church in these nations to perform all sorts of social activities on a mass scale, the same tax also diminishes the direct link between Catholics and church activities. Voluntary church activity and direct financial giving in these countries has been supplanted by a host of lay bureaucrats, many of whom sit rather loosely towards Catholic belief and essentially see themselves as deliverers of social services on behalf of the state.
The third data-point is that where Catholic bishops have promoted a “dynamic orthodoxy”, the Church in Western Europe has held its own. A good example of this is the archdiocese of Paris. Yes, that’s right—Paris, the home of the French Revolution. If you visit Notre Dame Cathedral in Paris on a Sunday evening, you will likely find it packed for evening Mass. The congregation typically consists of people of all ages and backgrounds.
Under the leadership of the late Cardinal Jean-Marie Lustiger and his successor Cardinal Vingt-Trois, the archdiocese of Paris has slowly emerged as a success story of post-Vatican II Catholicism. It has many vocations to the priesthood. It also has an active laity that is engaged with the world without being subservient to the expectations of secular culture. This “dynamic orthodoxy” has not involved retreating into a Catholic ghetto or yearning for an imaginary, idyllic 1950s in which a lot of social conformity often masqueraded as authentic belief and practice in much European and American Catholicism. Nor has it meant dumbing-down the faith to make it more “relevant” or “cool.” Instead, it has meant learning, living and teaching the fullness of the Catholic faith in the conditions of secular modernity. Part of the success has involved integrating many of the new Catholic movements—Emmanuel, L’Arche, Charismatic Renewal, etc—into the daily life of Catholic parishes in Paris.