I'd say it's not necessarily a religious facet, but an attraction to someone or something that would take over her life, some central element to orbit around, a sense of being part of something exciting and purposeful and bigger than herself.
I'd say that anyone who was vulnerable to joining a cult would also be vulnerable to getting sucked into devotion to any individual person who could create an aura about himself. I'd also say there would be an addictive personality at play - causing her to persist in the relationship despite pain - in the face of personal damage and estrangement from family and friends, loss of former lifestyle and dreams of the future, even loss of her own children.
You'd need to have a very weak sense of your own self to get involved in a cult and to give up as much as she sacrificed in order to first join the cult, and then stay involved with MG.
Maybe she was looking for a sense of surrendering to a power stronger than herself, the feeling of not having to negotiate life with all its complexities. That would be a mix of self abnegation and also avoidance of reality.