Have they ever slowed down?
The only reason they have not beat to death most Evangelical churches is because many are independent (e.g. Fundamentalist Baptist, Pentecostal, Non-denominational, etc.).
The large denominations of Christianity are easy prey.
Just the latest vesion of the "long march through the institutions" prescribed by marx and gramsci. When marx said to destroy all social conditions, he emphatically had the church and the family in mind as two priority tagets.