The Spirit of Faith
It's arguable whether the Faith of the Pantheon is more powerful than the high lords; there have been very few times when the populace has felt caught between loyalty to their house, and loyalty to their religion, and even when there have been -- such as the excommunication of High Lords -- the populace has felt torn. The high lords may control their lives, yes, but the Faith has sway over their souls.
But the one thing there has never been dispute on is that the Compact follows the Faith. When Abandoned bend the knee, if they've strayed from the path of the Faith in their long time away from the rest of Arvani society, it is expected they will swear to the Faith as a sign that they /do/ intend to be part of the Compact. Some keep shamanistic traditions on the side as well, of course -- it's hard to stomp out traditions entirely -- but they have always been expected to at least make a show of devotion. But even in the Northlands, the Faith is still powerful, especially as more and more people have married in over the years.
And the Faith's power has been growing.
Ever since the King's Rest, strange things have begun to happen. People claiming to have met or seen gods, people claiming to have witnessed magic. A belief in reincarnation. A growing interest in the power of the gods to hold these dark things at bay. As people have more recently begun to slowly take these seemingly mystical events seriously, more and more turn to the church for answers, reassurance -- and protection. To many of these people, shamanism seems awfully close to demon worship, and noble houses who cling to such strange beliefs even in the face of the Faith are viewed with some suspicion.
Indeed, the recent declaration that you must follow the Faith to minister within the Faith seemed, to most of the Compact, only sensible; even the people who have no quarrel with shamanism thought it reasonable. After all, the shamans wouldn't want a Godsworn coming in to lead shamanistic ceremonies, so why should the Faith allow shamans into the ranks of their priesthood and Discipleships?
So the fact that some people -- indeed, some /noble houses/ -- are grumbling their discontent catches most of the Compact off-guard. When the nobles you're supposed to pledge loyalty to, to emulate, seem to repudiate the Faith... what do you do? With rumors of demons on the rise, of magic returning to the world, it's hard not to be concerned for one's soul.
And so, eyes turn to the Faith once again for guidance and advice.