An Atheist's faith in ones-self to over come all obstacles in their path of life is still the power of faith.
The word "atheist" should not be capitalized. Atheism is not a belief system although it is a component in some belief systems.
I'm a Secular Humanist and we do have a faith of sorts that we are fully-equipped to deal with whatever life throws at us. It's more of a humanity as a whole thing than an individual thing though.
Not all atheists are Secular Humanists of course and some of those who aren't lack the convictions that they (individually or with the help of others) can handle whatever life throws at them. Those either fall to pieces, get a religion or learn to become comfortable with the idea that there is no super-natural power looking out for them.
People lose faith in their religion all the time. Some never get past mourning what they lost and desperately seeking to regain it while for others, it's like clearing one's head from a fog, an invigorating breath of fresh air. It's only "pointless and cruel" if they are in the former category. Apparently, Lynx can't comprehend that many people are in the latter.
One problem with this episode though is that it is exactly that: a single episode. Transitioning from a person of religious faith to losing that faith to becoming accepting (even grateful) of that loss is not something that happens overnight.