I was atheist long before I was vegan. My mind is rational and doesn’t work well with any deities. It’s because of my moral atheist mind that I believed we don’t have the ‘god given right’ to the earth or to animals’ products and I took the animals freedom and right to live into consideration.
There are more documented atheists than there are vegans. I believe that if veganism is being affiliated with atheism in either a good or bad way, it will still cause people to learn more about it. The more people who think about animal cruelty, plant based food health benefits, or environmental benefits of being vegan — the better.