You wrote:
“I wasn’t aware anyone actually believed that anymore.”
Incredibly it is still believed in by some Baptists even though there’s evidence for it. Even Baptists have repeatedly debunked it - including the former head the Southern Baptist Theological Seminary:
http://books.google.com/books?id=V68OAAAAIAAJ&printsec=frontcover&dq=William+Heth+Whitsitt
Whitsitt was tossed out of office for his research. Ironically, however, the grip that Landmarkism/Trail of Blood had on Baptists has steadily eroded since then.
I don’t understand why it is assumed a Christian group is not legitimate unless they can prove they were a “church in exile” during the Apostolic and Ante Nicene era.
There is no shame in Baptists having a late start in Christian denominational history. I don’t agree with all of their beliefs but they are Trinitarian and call upon Jesus as Lord and Savior. That is what makes them legitimate not the age of their denomination.
If age is what legitimized a sect then Gnostics beat out Baptists. Which I will stoutly claim is a big fat lie.