I guess from a fully-in Witness point of view, it's hard to reconcile the fact that the religion they are devoting their life to and which they fully believe is 'the truth' only manages to attract and keep about 1 in every 1000 people, despite an enormous preaching effort from the rank and file. Two explanations are:
A. Their religion consists of nothing more than dubious interpretations of an ancient book, that wouldn't convince any thinking person in the internet age.
B. People don't join their religion because they are being controlled by Satan.
From their perspective, A is obviously a non-starter, which leaves B. I don't know about you, but I'd be afraid if I thought 999 out of every 1000 people was possessed by Satan.