A chapter entitled "Parteiwahl und Nichtwahl: Zur Rolle sozialer Konfliktlinien" has appeared in Wahlen und Wähler: Analysen aus Anlass der Bundestagswahl von 2013 (ed. by Harald Schoen and Bernhard Wessels) and is now available from Springer.
One of the most striking findings in this chapter is that the social democrats are no longer the strongest party among manual workers, a large segment of whom has decided to abstain from the election, and that non-voting now is stronger related to class than SPD support. On the other hand, the impact on church attendance is still strongly related to the support for the CDU/CSU.
A more detailed analyses can be found in the chapter, of course.