Fascinating as this discussion is, it is all conjecture. I'd be interested to see statistics concerning how many people in the United States self-identify as progressives and how many consider themselves religious.
I think you'll find 'progressives' make up a substantial portion of the population; atheists do not. But again, both my position and yours are meaningless without figures.
But this can be said: Progressivism isn't an ideology guys, so it can't be inherently for or against anything except for that which it must be by definition: i.e. for progress and against regress. We typically use it to mean, someone who favors reform and change, generally using the government as an instrument to that end.
But we also call environmentalists, feminists, civil rights activists, and the like progressives. Sometimes they prefer to inspire change through outreach programs sponsored or run by non-profits or other sorts of NGOs.
But again, progressivism isn't an ideology. Unlike Marxism or Libertarianism you don't need to believe in any particular normative and empirical worldview. If you have a problem with atheists, and the fact that many atheists believe in Reform Liberalism, Democratic Socialism, one of the variety of schools of straight Socialism, Marxism, or political Feminism (which is a coherent ideology, although it has come to be used really broadly as well), then you need to specify. Especially because each of these groups views religion differently.
Take Marxism, for example. Marxists have no qualm with religion. They simply believe that once they have created the Communist utopia, government and religion both will no longer be necessary. Marx thought that people needed religion to help cope with the harshness of life, so naturally, once life was no longer harsh and unfulfilling, people would give up religion.
Socialists, on the other hand, seem to have historically taken a very strong anti-religious stance. Though there has been some variation.
The point is, progressives can't be anti-religious because they have no coherent normative/empirical shared beliefs. It's just another political buzzword people use.
It's used the same way people use 'conservative'.
Libertarians, Fascists, Traditional Conservatives, and Christian Dominionists in this country all fall on the conservative end of the spectrum and call themselves conservative. But they all share radically different beliefs and would be at each others throats if all of the left-of-center ideologies disappeared.
Likewise, 'progressive' is an umbrella term - Environmentalists, Feminists, Modern Reform Liberals, Socialists, Democratic Socialists, Marxists, etc etc. And these groups are only superficially similar. If the right-of-center parties all disappeared these guys would ripping each other to shreds.
So if you want to end this 'war on religion' you're going to have to find out who it is you're actually fighting against. Find out what the anti-religion 'progressives' have in common. Otherwise you just end up making pretty wild accusations against a huge variety of people. It's like when conservatives are called racists. There are racists in the conservative party, but it's not because they're conservative. It's because they're racist.