Why is it that secular democracies and republics continue to require oaths (or affirmations) from their public officials? As Aroney puts it, "Oaths of office come to us as vestiges of a previous age, or so it seems. They belong to a time when duty was prior to right and religious sanction was taken for granted." But that time has long passed. Or has it?
Aroney, citing to Carl Schmitt, observes that "all of the important ideas in our modern liberal politics are secularized theological concepts." Thus oaths, even in this secular age, bear a tantalizing witness to the submerged reality which upholds the liberalism that denies the existence of that reality. In particular, oaths remind us that there is sovereignty behind and above the current political sovereign.
There's much more to read in Aroney's short (16 pp.) piece. I highly commend it to my readers' attention.