Environmental factors that predict theism Are there any environmental factors which can predict atheism or theism?
Your question specifically asks environmental factors which predict theism/atheism. Although your question is quite simple, it actually raises quite a few complexities. 

Firstly, are we referring to religiosity, or specifically a belief in god? Many studies examining the psychology of the religion fail to make this distinction clear. Most probably because belief in a god is implied by active participation in religion - though I would say not an exclusive rule. It would be interesting to consider the multitude of pathways in which people get drawn into religion (a cultural institution) compared to a belief in god.

Secondly, your question specifies only the predictors of religious belief that are environmental. From my limited experience, this really closes off several of the most important predictors of religiosity (e.g. personality, attitudes). This makes it difficult to answer the question effectively. Most probably, religious belief can be predicted by a range of both individual level variables (e.g. personality) and environmental (e.g. parents religiosity) - and these variables likely interact with each other (i.e. some personality traits increase likelihood of being influenced by parents religious views).

Finally, the question is complicated as the predictors for belief in god may not be related to predictors of atheism. For instance, if low-socioeconomic status predicts theism, high-socioeconomic status may not be a good predictor of atheism. 

I conducted a google scholar review using terms such as: "predictors of religiosity" "predictors of religious". From this, I focused on longitudinal studies and those which focused not simply on personality/cognitive traits. Examples of studies which I found were Predictors of Religiosity Among Youth Aged 17–22: A Longitudinal Study of the National Survey of Children which found 


  The best predictors of youth religiosity were ethnicity and peers'
  church attendance during high school. Other predictors were, in order
  of decreasing magnitude: residence in the south, gender, religious
  schooling during childhood, maternal religiosity, church attendance
  during childhood, the importance mothers placed on childhood religious
  training, and an interaction variable identifying religious mothers
  who were very supportive.


and Explaining religiosity: towards a unified theoretical model.


  Individuals had a much
  higher probability of showing Christian religiosity if they had been strongly
  socialized by their parents, if they came from a mono-religious household and
  if they had Christian peer-socialization. Deprivation, social control, religious
  tradition of the canton as well as gender and age also played a certain role.
  Individuals with less education and income, living in smaller and rural communities
  and in traditionally Catholic (or mixed) cantons had a higher likelihood
  of showing Christian religiosity. The latter finding is very similar to that
  by Norris and Inglehart (2004) who were also able to show that religious
  culture was important on a collective (national) level. Furthermore, the study
  shows that especially older women had a much higher probability than
  younger women to be religious, while age was much less important for men.


A major criticism of the literature (as it currently stands) is that a large proportion of the quantitative work focuses on western, predominately Christian samples (see Vassilis and colleagues for more information). I would argue the book is open on this one. Clearly, thought has been placed into this field and there are some logical environmental predictors (i.e. parents religious views); however, few of these have been replicated in representative samples.