It could have been better expressed . . . but the WaPo was clearly using the "speaking in tongues" as a slam. The writer understood (correctly, I think) that the WaPo holds no brief for charismatics and was just trying to make the church look as weird and Bible-thumping backwoods as possible. They probably would have claimed they saw people in overalls and brogans kissing rattlesnakes and drinking strychnine, if they thought anybody would believe them.
A mainline Episcopalian was insulted -- but the WaPo intended to insult him.
Quick - get 'em some borage!
I guess it's like calling someone a redneck: Some people will respond, "How dare you!" and others, "Yeah, so what?"
You should make that "formerly mainline Episcopalian." Today's mainline Episcopalians are an entirely different species.