Well, that's all well and good. I see your happiness statement as sort of a blanket statement and I understand where you are coming from there. Now that I am on the other side I see things differently than you do. I can make a comparison between my happiness as a Christian and my happiness as an atheist. Know what? By and large there isn't much difference. Being religious had certain benefits regarding happiness and being atheist also has distinct benefits regarding happiness.
I have atheist friends and Christian friends and their happiness seems to have much more to do with other factors, as one might expect.
Also, the devil is in the details of the faith. When certain details fail to make sense, then more and more will unravel. If you are left with a general belief in god, then you are either deist or a general theist, but not Christian.
He wasn't saying atheists can't be happy or aren't happy, or even that religion is needed for happiness. Statistically, religious people are happier.