I'm in a similar boat, but I understand there are options out there.
One, there are public meetings in and around Austin where like-minded people congregate. I haven't been to any of them yet, but I plan to put it on my to do list.
Two, online dating makes this a lot easier, too. You can clearly let it be known that you are atheist and there are usually fields that specifically ask for religious preference, with Atheist and/or agnostic as options a lot of the time.
Good luck finding your partner. I'm still keeping an eye out for the right rational girl for me.