Who could look more devout than the Dalai Lama? Yet his god is the Devil.
The all the gods of the heathens are devils.(Psalms 95-5)
Practically all religions have devout looking groups. Charismatism is not Catholic. Those people your nephew saw are just like any other devout looking non-Catholics.
Besides, who is your nephew?
Have you ever attended a healing Mass and witnessed people slain in the Sporot and healed?
If not you need to.....the Holy Spirit does the will of the Father and Son, remember? In our world today! Remember?