I think it would be safe to say that most atheists feel depressed, frustrated, and impatient from time-to-time over how slowly things seem to be improving when it comes to subjects like secularism, religiously-motivated bigotry, human rights, and reality-based policy. Many of us who live in predominately religious areas may feel discouraged that our neighbors still haven't come to their senses, leading us to feel like strangers in a strange land. "They believe what?" "How can they still believe that?" There has been progress, to be sure. That cannot be denied. At the same time, I think it is clear that the pace of this progress has been much slower than most of us would like.
In this context, one of the things that gives me hope when I find myself needing it is the simple act of remembering that there are ex-Christians, ex-Muslims, and so on. Most of us know some of them, and many of us are some of them. If I stop and consider the fact that there are people (people like me) who were indoctrinated into a religious tradition, believed for several years, and then managed to leave it behind...well...I cannot help but feel more hopeful. It isn't just that people can change; it is that people do change. After all, many of us managed to do so and most of us know others who did so too. Reminding myself of that fact gives me hope.
This would be valuable even if that was where the story ended. But this story does not end here. I find that there is another important benefit to reminding myself that people change and that many of us managed to overcome religious indoctrination. In fact, this other benefit might even more important than hope. So what is this other benefit? Remembering ex-believers improves how I treat current believers, as well as atheists who are at different places in their journey away from religious belief.
I cannot bring myself to hate religious believers merely because they are religious believers. They deserve the same opportunity to learn that they are mistaken and move on that I had. And even if they do not do so, being wrong does not make them bad people. If it did, we'd all be bad people. Similarly, I can't judge atheists too harshly for being angry at how they've been treated by religious believers. Hell, it makes me angry to hear how they've been treated. Even though I now recognize that lashing out at religious believers because one was treated poorly by other religious believers accomplishes little, I can't pretend this was an easy lesson or one I learned quickly.
I guess what I am saying here is that recognizing former religious believers helps me feel more hopeful about our future and helps me be a better humanist in my day-to-day life. Neither of these things come naturally to me, so I am grateful for all the help I can get.