It is often difficult, or even impossible, to present an absolutely comprehensive case against someone's position and in favor of your own method and position in the same forum. Billboards, books, blog posts and public events only allow so many words. One does not always get the chance or have the time to fully outline their reasons for critique. But this does not imply that one does not hold good reasons, or thinks that reasons are unimportant. It only suggests a different approach.
For example, Christopher Hitchens is a proud secular humanist. But he spends more time writing and speaking about religious belief than he does clarifying his moral worldview. Is there any reason to doubt his secular humanist credentials because of this? Is his critique of religious belief not helping foster a secular humanist society? Is he really doing harm by increasing the amount of public discourse on religion?
In the end, I believe this is a mistaken debate between people with slightly differing interests. Slightly is the operative word here, for both groups would certainly be considered members of the same team. Many of them even work together at the same secular organization. The critic of religious faith and dogma is on the same side as the promoter of secular moral values. To squabble about whose interests are more important is to lose sight of the underlying problem: the staggering amount of uncritical thinking that is putting society to ruin.