In Economics, secular essentially refers to long-term trends regardless of boom-and-bust business cycles. The focus is on the long term. In the context of economics it has nothing to do with religiousness.

A secular trend is a variable that evidences a consistent pattern within a given period of time. It is a statistical tendency that can be easily identified and it is not subject to seasonal or cyclical effects. (https://www.myaccountingcourse.com/accounting-dictionary/sec...)

'Secular' has multiple definitions; this one refers to a non-cyclical trend:

https://www.lexico.com/en/definition/secular

From context, the OP is using it to mean, over a period of time.