If the people of a state have decided that they will allow each other to open carry, the common citizen has no business calling the police if they feel threatened by someone with a rifle in public. There are a myriad of videos online of people peevishly strapping a rifle on their back and filming their open carry walk through town expressly for the purpose of laying into police officers and citizens who are concerned for the community well-being. The very people who are afraid are the same that validate the hubris of those who intentionally provoke their fear.
It has been agreed that this behavior is reasonable, and no citizen should be alarmed by it. Yet the natural reaction of both citizen and the police when they see a man openly carrying an AK-47 on their back down main street, what right do they have for alarm? They have legally agreed that the burden is on them to get over their fears, not on the gun owner to refrain from scaring them. This is at best hypocritical and at worst masochistic, or something far more insidious about which I will not speculate.
France and Belgium—both countries that have virtually outlawed guns in any private form—have each been subject to a major shooting rampage recently, both of which were related directly to radical Islam. However, we have had dozens of attacks ranging from religious radicals to the shooting of children like rats in a bucket in Newtown. From Charleston to Orlando to Aurora to Columbine, the motivation behind mass shootings has always been the result of some kind of sick ideology, be it racism, religion, misplaced anger from a warped societal view, or the machinations of a deluded mind. To single out religion as if it is somehow a special case is to give oneself license to exclude anything for any reason.
In fact, the idea of gun control, either soft or strict, is by definition a question of the special case, e.g. prevailing social opinions of each state's electorate. It's their prerogative to decide how far to take the 2nd Amendment which is currently a non-negotiable article of state. There are innumerable reasons to exclude and include nebulous or well-defined ideologies about the nature of people and the danger we, or the government, or whatever you like present to one another. If the public wants guns they can have them. Unfortunately, in no place in this country can the public choose to remove them. The scale is by its very nature unbalanced. The 2nd Amendment quite literally holds the opposition hostage at the barrel of a gun.
That is the difference between the European tragedies and those on US soil. In France, religious radicals are able to carry out attacks only because they are willing to do absolutely anything to smuggle weapons into the country, and risk getting caught even at the point of attempting to bring in a single bullet. However, in the United States the man who is willing to shoot up a school need only drive a few miles to a gun store without having to worry about setting of ten different law enforcement alarm bells along the way to get the goods. When all the elements for a mass shooting are readily available, it is simply a question of when, not who or why.