I think our own biases play a role in what level of atheism most come to. For example the four authors mentioned have very different backgrounds. The 2 that are more anti theist Dawkins, and Dennett were raised with religion. Haidt, and Harris were not.
This does not take away from the veracity of their viewpoints. I just think it's important to know where one is coming from when considering their viewpoints. For example while I understand why Dennett and Dawkins refer to religion as a virus, I now find that viewpoint to be overly simplistic and incomplete.
Just because religion helped us along the way in our development. It does not mean that it is right. Anymore then how our compassion for others drops when the number in need gets larger. I believe we need to grow beyond our baser instincts. In order to do that we need to understand how religion developed and what function it served.