Honestly , while every one will need to make changes in the way they act and think , the majority ofbtge action need takes place at the political and industrial level.
Animal agriculture increases the cost of food and decreases the amount available . it uses way more water and land . Animal agriculture, particularly beef, is a large green house gas emitter . All of those are bad for people .
Many atheists are also agnostic.
Me personally I don't believe in any gods and I don't believe any exist. I'm still open to being wrong but as it stands that's how I feel.