Works, but there were some changes in the legacy tree that will be undone, another way to make it available at least to players is to use

can_be_picked = {
OR = {
faith = {
has_doctrine = tenet_divine_purity
}
is_ai = no
}
}

That way the AI won't be able to use it if they don't have divine purity as a tenet.

Still works, just make sure you put it in second in your playlist!

Desperately needs an update.

Hope this gets updated, pretty important mod T-T