"Marry only in the lord means to marry another Christian. Doesn't mean to marry only in your own CULT religion. That's what the G.B. want so they can be controlled."
When Paul wrote "Marry only in the lord", he did not limit it to only those who read his writing and followed his writings and went to the meetings that he arranged. He focused on the belief and following of the Christ. But the GB wants it to be only people who follow what they wrote and their meetings.