In my not-so-humble opinion, this is exactly the right message (though I should make clear that I'd include some of the nicer, politically reasonable, theists and cultural religionists in the "who knows what else" category).
On the one hand, anyone who is for individual liberty, tolerance, reason, and science, and against dogma, authoritarianism, and the various moralities of misery that we find in the world is likely to be fine with me. I'm putting in the words "likely to be" because some people who'd see themselves as falling under that description can nonetheless have moral and political views with which I want no association. For example, I don't think that I'm going to be able to work well with the most hardcore Randian libertarians, though some individuals with libertarian leanings, such as Ron Bailey, may be valuable allies in the political struggle against neo-Luddites.
On the other hand, any alliances I have with any of these people - whether over specific aspects of my own agenda or over the broader struggle for a genuinely liberal and compassionate society - shouldn't make me keep silence about disagreements.
All that said, we live in a world where many kinds of deep conservatism seek to control political power, to the detriment of our freedom and of human advancement. Worse from my viewpoint, elements of the Left have been dragged into an alliance with traditional conservatives over such issues as genetic technologies. Those of us who strive to form a party of reason need to establish the broadest alliances that we meaningfully can.