"No, NAT isn't a firewall. Not even close to being a firewall."
you are arguing semantics and terms. Keep in mind that I've done kernel programming with netfilter modules on WiFi routers for money (it was a while back, but there ya go). Now, THAT is a firewall for sure! Not like the joke that Micro-shaft excreted for windows boxen.
And your average NAT router runs netfilter/iptables (surprise!). And NAT does that one thing that firewalls are supposed to do: It stops intrusions from attempted connections on open ports, by blocking them. FIREWALL. Deal with it. I'll get my coat. Anything further on this topic, with someone who argues terminology and semantics, is a colossal waste of time.