Granted, but he uses thanking God and believing that life has a purpose as examples of the delusional thinking that he says we need to abandon -- implying that there can be no truth or substance to such beliefs

You could make another case about what he thinks, though... something like

"Since we haven't demonstrated Heaven exists through a rational analysis, we can't know there is such a place or state of being. So thanking Heaven is premature, though possibly correct."

This is somewhat different from, and more open-minded than,

"There is no Heaven. Therefore, thanking Heaven is meaningless."

But I think you're right, and he actually means the second.