Spirituality and religion are different things. Spirituality is basically an attempt to find meaning in life by identifying with something that transcends the self. Religion can be one way to try to achieve that, but is just a set of norms and myths used to try and understand existence and our place in it.
Spirituality can be secular and is by no means a bad thing. It doesn't even have to be irrational or unscientific. Asceticism is a spiritual practice adopted by many religions and is thought to help one focus on spiritual enlightenment. Lent is an ascetic practice.
Imo this is very much a case of "to each their own" and, as long as it isn't hurting your brother or anyone else, then it may help him find more meaning in his life.
TL;DR: approval down 1% from 45% to 44% over 6 days. Was at 47% on Jan 20. Disapproval up to 51% from 41% though since January.