John Hudak summarizes:
While diversity has been a key to Democratic success in recent presidential elections, it can also make coalition management difficult. The Democratic coalition is made up of the least religious Americans (17 percent of Democrats are religiously unaffiliated) and the most religious Americans (African-Americans). This is reflected in the religious and theological orientation of the parties. The relative homogeneity of the Republican Party means there are fewer tensions but points to long-term challenges, since younger voters are less religiously affiliated and more progressive on many social issues, particularly marriage equality.The reports points out that there are advantages and disadvantages to the religious diversity found in both coalitions. As an atheist, I am happy that the Democrats are orienting themselves towards the least religious Americans.