Ronald Inglehart in the context of "Comparative politics"

In sociology, secularization (British English: secularisation) is a multilayered concept that generally denotes "a transition from a religious to a more worldly level." There are many types of secularization and most do not lead to atheism or irreligion, nor are they automatically antithetical to religion. Secularization has different connotations such as implying differentiation of secular from religious domains, the marginalization of religion in those domains, or it may also entail the transformation of religion as a result of its recharacterization (e.g., as a private concern, or as a non-political matter or issue).

The secularization thesis expresses the idea that through the lens of the European enlightenment modernization, rationalization, combined with the ascent of science and technology, religious authority diminishes in all aspects of social life and governance. Pew Research Center notes that economic development is positively correlated with less religiousness. According to Pippa Norris and Ronald Inglehart, "virtually all advanced industrial societies" have become more secular in recent decades.

Self-expression values are part of a core value dimension in the modernization process. Self-expression is a cluster of values that include social tolerance, life satisfaction, public expression and an aspiration to liberty. Ronald Inglehart, the University of Michigan professor who developed the theory of post-materialism, has worked extensively with this concept. The Inglehart–Welzel Cultural Map contrasts self-expression values with survival values, illustrating the changes in values across countries and generations. The idea that the world is moving towards self-expression values was discussed at length in an article in the Economist. Expressing one's personality, emotions, or ideas through art, music, or drama, is a way to reveal oneself to others in a way that is special to them.

The Inglehart–Welzel cultural map of the world is a scatter plot created by political scientists Ronald Inglehart and Christian Welzel based on the World Values Survey and European Values Study. It depicts closely linked cultural values that vary between societies in two predominant dimensions: traditional versus secular-rational values on the vertical y-axis and survival versus self-expression values on the horizontal x-axis. Moving upward on this map reflects the shift from traditional values to secular-rational ones and moving rightward reflects the shift from survival values to self-expression values.

According to the authors: "These two dimensions explain more than 70 percent of the cross-national variance in a factor analysis of ten indicators—and each of these dimensions is strongly correlated with scores of other important orientations."