Or more exactly between "ancient" and "new" world.
Further to the religious wars, Europe stands out in religious spheres of influence mono confessional stemming from the advent of the Protestantism in front of Catholicism. These zones of infuences are so often the resultant of wills of the sovereigns of period to want to free themselves or not from the guardianship of Vatican.
The countries where the bourgeoisie had a certain influence, which wanted to free itself from the guardianship of the nobility, knighted by the papal power, opted generally for the Protestantism. It is generally countries which evolved towards an elitist bourgeois democracy. So the mountainous countries which offered to the Protestants a more safe refuge in the wars between religious, where the democracy of the people will be established more naturally.
The countries of the South, which were closer to Vatican geographically, stayed under its influence. In spite of they were closer to the Islamic world and needed a certain unity in front of its hegemonism. So the nobility was more prégante there, and saw in the Catholicism, which knighted it, a good means to consolidate its dominant position on the populations.
Ideologically, the South remained attached at the idea of a social structuralization where the material and spiritual life was determined by the good will of the elites of the monarchic and spiritual nobility. While in the North it established itself on the free personal interpretation of the fact that had to be the spiritual and material life thus.
The essort of the capitalism was for many there: Vatican condemned the business of the usurers, the prototype of merchant banks. The middle-class persons thus preferred the Protestantism which offered them better perspectives of development.
England was a particular case where the monarch frees himself from Vatican by establishing a kind of Catholicism of state. Nevertheless the bourgeoisie eventually imposes it its power to the monarch.
Tsarist Russia also had its orthodox sense of identity, or the tzar reigned over the contingencies material as the church reigned over the spiritual life, a kind of monarchic secularism. Napoleon, stemming from the french revolution will get back the concept by taking his emperor's crown of the hands of the Pope, come (summoned) to crown him emperor, to put himself his coronne on the head: he so meant that his crowning was not an allegiance to the papal power.
Historically the United States of America were also an earth refuge for all the persecuted of the religious wars. Many of European migrated in Europe to lands where their confession was there largely majority. But ideologically United States corresponded to them better: a piece of news is in hiding for a new religion. So numerous minority religions had no land of welcome identified in Europe. De facto the USA is a country theist.
The secularism enters "ancient" and "new" world
The precursors: France and United States
France is not a country theist, but rationalist by definition... It would be inconceivable that the head of state throws a war in Iraq, or somewhere else, under God's banner as Bush for example. The French secularism includes not only the religions but also the philosophic currents such as the atheism. And the state does not have to immisser in the religious affairs, except when it disturbs the law and order.
De facto the atheists and their thought are established, and are very infuents (34 % of the population) there: they speak of equal to equal with the monks. The relationship is not any more for a long time of dominating in dominated, the time helping the debate is there more serene, whatever inevitably tightened (inevitably stretched out). It is the French-style secularism. We have a special word for it : the "laïcité"-sécularism). To see even the monks tend to consider the secularism as too favorable in there free thinkers to their detriment, although it guarantees them their freedom of worship.
So a nuance, the American secularism dates the independence, The Anglicanism recognized king of England as head of the church. The independence broke any link between the official church and the political power by guaranteeing it, so by attracting all the monks persecuted by Europe and moreover. It is a society pluri religious or the religion is not lived as source of power, but as source of emancipation with regard to the " old world ".
In France the revolution tried well to establish a constitutional monarchy, independent from the church, but the monarch tried to run away abroad to get back better the power by the strength with the support of the other European monarches. Actually, the Roman Catholic Church claim to have to knight always catholic monarches under its authority, who held their legitimacy of God thus. They was enough for the Americans to free themselves from the britain crown to be independent, But French had difficulty in freeing themselves.
The religion (essentially catholic) is thus lived there as a threat of subjection, and not freedom.
Let us note in the passage, an important theological nuance in the piracy: in Seas remote from colonizing states, there was enough ilslands except controle so that the piracy blooms freely, but in Europe no port been able to offer to them of safe refuge. So the pirates made corsairs (privateers) there by concluding agreements with states at war perm between them. The deal was that these states offered them the security of a port of registry as long as they attacked only enemy ships, for a discount on their fixed prices. The most malignant decanted a part of their booty on embarquations girls in the wide to claim not to have made big booties during their exit (release), and to underestimate so their tithe to the protective state.
In United States when a moralizer Pastafari preaches in the street, we say ourselves " It is beautiful the freedom to believe in what we want ", in France it would be rather " In which yoke he wants to enslave me that one " (certainly in collusion with the state).
Thus theological nuance, for us the religion is bad in priori, not in term of faith in God in itself, no, but as institution capable of compromising with the political power to enslave us better. So the tea poisoning agnostism is not lived as threatening: this theist abounding in a "official" religion, and especially in no precise dogma which he doubts in priori, does not risk to get closer to the political power to impose his point of views which it doubts himself, but in the limit to protect itself simply its freedom, and thus that of his neighbor. What suits well enough in most of the atheists who ask only for a matter, it's that we do not impose them lifestyles and politics inherited from the religious thought. Later in each to impose upon himsel the religious rules, or not, which suit him.
What does not prevent the debate moreover: we shall sometimes try to convince the believer that he will not go to hell if he breaks his rules, as we shall try to convince the superstitious that he is not afraid of nothing to cross the road of a black cat, but without any more, with sometimes, it is true, a headland of pity for the one who offends the piracy.
The mistrust to the religions is thus more marked in countries historically catholic than Protestants, not as long thus face to face religious faiths in itself, that face to face religious organizations which head them by exercising their lobbying machiavelliques thus.
Please note: the Catholicism is not a handicap as a majority religion in the "laïcité". Certainly its lobbying is there very powerful in France dividing between 29 % of Catholics and 34 % of atheists (30 % of agnostics), but at least the religious pressure is not scattered there: the interlocutor is clearly identified with it. So when the Pope takes a fundamentalist position everybody falls him above, including of numerous Catholics who do not recognize there, and abound then in the secularism. Also in many countries more mainly catholic the secularism allows the believers to take their distances with the religious dogmae.
In Protestant country and more specially in United States the interlocutors are more diffuse, and thus connections between politics and religions. The sécularisme defends itself there as intrinsic value, and not as opposition to a public philosophy of life clearly identified religiously.
The secularism eventually imposed in Europe by the development of the capitalism, where the faith in the rationalisms "bizness" and especially scientist got the upper hand over the faiths theists, relegated then in the background. Making it, the northem protestantism and the French-style secularism eventually moved closer in the dévelloppement of the atheism and the agnosticism there.