Less than 10 percent of Americans call themselves atheists. I haven't seen a poll on those who call themselves "secularists" but I wouldn't be surprised if most of the Dem votes should term themselves such.
So it seems pretty safe to say that secularists vote Dem.
Anyway, the closest I can come would be this survey of voters which indicate that 58 percent of those who attended church weekly voted for Bush over Gore (and that would include the black church-goers who went for Gore), while 65 percent of those who never attend church went for Gore.
So it seems pretty safe to say that secularists vote Dem.
So you assert that if someone doesn't attend church every week, they are not religious, and by your definition secularists? BTW, does the church they attend matter in your calculations?