I’m afraid I don’t agree…
Five objections come to mind:
1. Atheism doesn’t imply any particular worldview. It’s merely not believing in something. Nothing more. To suggest otherwise is equivalent to averring that not believing in unicorns represents a coherent set of beliefs about something else. No. It simply means that one doesn’t believe in unicorns because one has never seen one, nor is aware of anyone else having ever seen one. That’s all there is to it.
2. Religion ought not to be redefined so as to encompass any system of values. Religion implies beliefs and practices at whose very core lies the idea of a supernatural being that created the universe and that, typically, is very much concerned with our actions and thoughts, which it constantly monitors in order to decide whether to punish or reward us in the afterlife (or some variation thereof). The concept of religion cannot be arbitrarily extended to include non-theistic beliefs, values and practices. If religion is redefined so broadly, it just loses its meaning. It ceases to be a useful word. The meaning of words relies on convention: the current convention of its meaning restricts it to theism-related (or at least “supernatural”-related) notions.
3. Not everything is equally probable, thus not everything deserves equal credence.
4. Non-religious views can and do change and evolve. Religious views tend to be, by their very nature, far more static. Furthermore, they are not to be questioned or challenged (non-theistic orthodoxies can of course also reject criticism in a nearly despotic fashion, but, if obviously detrimental, they will normally evolve—or completely disappear—more rapidly). This is an important distinction between theistic and non-theistic beliefs.
5. Finally, an argument that relies on reason and rationality to claim that reason and rationality are unreliable is self-defeating and inherently contradictory. Why should one trust the rationality supporting an argument if the argument in question rejects the very rationality on which it intends to rely?