I found God via the JWs house to house work, I also belive the JWs to be pretty much as apostate as all the other religions of Man.
Doesnt mean Jesus cannot find his sheep anywhere they happen to be.
Jesus said the very stones would cry out, and they are not a religion, maybe the illustration of the Kingdom of God being like a dragnet that brings in fish both suitable and unsuitable is applicable here?
I expect Jesus finds his sheep in the Catholic church as well.
The question will be, when Jesus does return, his Sheep will know his voice and fellow the good Shepard wherever he goes, that means they will leave thier Apostate religions, those that worship their religions will remain and not follow the good Shepard, they will not recognise his voice because they prefer the voice of the JW GB
I expect if Satan himself was to appear at peoples doors, horns and all, the experience would make a lot of people jump into Jesus arms.