I wonder if the view commonly promoted by Christians - that there is a lot more sex before marriage than there used to be - is due to people getting married later than in previous generations? Rather than being entirely the result of the permissive sixties it would seem that house prices and the need to have both partners working is the reason people delay marriage to their late 20's or early 30's.
In the days when people got married at 18 or 19 it was more possible to control those urges for the short period of time, but delaying for 10 years or so is a much harder proposition.
If the church wants to discourage sex before marriage then they need to encourage early marriage and endorse social policies, like increased social housing, that make this possible. I would guess that evangelicals would rather continue to condemn sexual activity than have to endorse progressive political agendas, or would they?