It's hard to tell if Europe has less religious bigotry for a couple reasons
1) There are almost zero immigrants in a lot of Europe when compared to the US. Comparing cultural tolerances in places which have different quantities of immigrants is really hard.
Dude, that's been untrue for almost 20 years. The idea of the USA as the big melting pot vs the monocultural Europe is complete nonsense. Almost 40% of people in Belgium (and we're smack-dab in the heart of the EU, not on the borders, so compare us to, say, Kansas or Colorado, geographically speaking) has roots in the last 2 generations outisde of the EU. It goes up to over 60% if you include other EU countries (and yes, Spain or Finland or Poland have a different culture than Belgium or each other.) Literally over 50% of children born last year had parents of a non-EU origin. There are now more practicing muslims than practising Christians in Belgium (according to official figures from 2010).
2) On the other hand, Europe is simply geographically closer to a lot of foreign cultures, like the middle east, which means that the influences you feel from them may be stronger than we do. Similar to the immigrant thing, but different side of the coin. Americas southern border brings in a strong Catholic influence, but it's northern border is culturally insignificant. There's a reason we call Canada our hat.
Meh, you're saying Canada and the US are one and the same culture throughout? I don't agree at all, but let's agree to disagree.
3) While Europe may have less religious bigotry, it also may have less religious tolerance. France is a good example of the kind of laws that would NEVER be accepted in the US (outlawing Burka's in public or religious symbols in public schools.)
On the other hand, school books presenting creationism as a valid scientific theory on the same level as evolution would NEVER be accepted in practically all of Western Europe. Different emphasis placed on different things. Outlawing religious symbols in public schools, to me, points in entirely the opposite direction: it's a sign of acceptance, plurality and tolerance, not the other way around. Public schools, run and paid for by the state, have to be neutral, open and inviting to everyone. Loading them up with crucifixes, praying before the school day, taking the class to mass,... are not acceptable when you're dealing with people of dozens of religions.
Anyway, the difference in what would be "acceptable" and what not, is mostly one of the way you look at religion. In (Western) Europe, it's quickly becoming generally accepted that religion is perfectly fine, but no religion whatsoever should meddle with/interfere in public life on any level. Do whatever you want in name of your religion - but do it at home, out of sight, and without showing it or forcing it on anyone else. Be it slaughtering a sheep according to religious rites, fasting a month, covering your hair, circumsizing your children, baptising your babies, or whatever.
In the USA, just like in most of the Middle East, there's still a significant part of the population which believes a church (no matter which one - the one those people happen to belong to) has a right/obligation to try and enforce
their ethical and moral views on the rest of society. Whether you're a muslim stoning a woman for not covering her hair, or a christian threatening women who need an abortion, it's equally disgusting and dispicable.
Your religion is
your concern, not mine. Don't force it on me and I won't force mine on you. Living according to the Sharia or according Leviticus is equally backwards and against my - and many Europeans - principles.