A national survey in 2014 for the Austin Institute showed that:

56% of evangelicals between ages 20 and 39 were currently married. Only 42% of the rest of the same-age population were married.

A repeated survey in 2018 showed a decline for both:

51% of evangelicals 20 to 39 were married 40% of the same age in the general population were married.

From 2014 to 2018:

The number of evangelicals cohabiting rose from 3.9% to 6.7% In the general popular support for cohabitation went from 16% to 27%

Very few of the surveyed evangelicals believe that marriage is “outdated,” but a growing minority of them now perceive an alternative pathway to get there.