No idea why everyone is hyping the Humanism so much.
Actual religious unity beats out artificial unity by a large margin when playing a catholic country. So I guess its only really worthy to take as protestant or reformed when big, but when youre big catholic is a lot better. So its not really useful at all. People seem to have many problems with rebels when they value the bonuses so high, BROT is good, ideacost is solid, culture is good, - RR is solid. Nothing to call OP though. Cheaper/faster culture conversion from religious is also an interesting change.
If you're Reformed and you focus on Stability you get -2 revolt risk. So that base -4 revolt risk from Humanism.
You also get +5 tolerance of heretics from being Reformed + Humanism and +3 tolerance of heathens from the same combo.
So, basically you have -4 revolt risk in Reformed provinces, -9 revolt risk for heretic provinces, -7 revolt risk for heathen provinces.
If you're in the HRE or you join it, that's -7/-12/-10.
Add the lack/much shorter of nationalism and the lower threshold for accepted cultures and you can get some crazy revolt risk going without skipping a beat. Like say, when you've got huge overextension
So Innovative + Humanist + Poland/Commonwealth/France+Edict of Nantes = minimum 75% Religious Unity? Even when we consider that somehow not a single province grants you religious unity?
Innovative's bonus has moved to Humanist. So only +25% minimum religious unity from idea groups.
And if you want high religious unity, get the Timurids => 50% base. Timurids + Humanist looks really strong now - for certain play styles.