Progressive taxation is a Christian heresy based on a loose interpretation of Luke 12.48b, as if it justified charging one rich man 33%, another 35% and still another 39.6%, while charging one poor man 10%, another 15% and a third 25%:
Every one to whom much is given, of him will much be required;
Literally ripped from its context and mangled, the passage is made to teach something completely at odds with the apocalyptic setting of the chapter (which mirrors Matthew 10), its coming Son of Man figure (vss. 8, 10, 40), its urgency about the end of the world and the judgment which comes with it (vss. 20, 28, 40, 46, 49f., 56) and especially its call to repentance.
The latter consists of liquidation of assets, distribution of same to the poor (vs. 33), and utter dependence on God (vss. 24, 27, 29-32). It doesn't matter whether one has much or little when answering the call to come and follow. The price is always the same: everything you've got. That is the sense in which those with much have much required of them, but it is also the sense in which those who have little have little required of them. Nevertheless it is all required, whether much or little.
Accordingly it is complete nonsense to suggest that such a Jesus has anything to say to us about taxation. He doesn't imagine the world will even last long enough to develop the immanentized utopia of liberal dreams. But even if he had, who would fund it? Certainly not his disciples, who would have no jobs to tax, having left all to follow him. If Christianity is anything, it is renunciation of the world, not this uneasy truce we see living out its years everywhere.
What's almost worse than this perversion of history is progressive taxation's theocratic hypocrisy. The liberals who advocate progressive taxation often seem to find nothing wrong with scaling the wall separating church and state to pluck this bon mot for their cause while at the same time decrying every conservative who does the same in support of traditional morality, for example. The reason liberals do it surely is sinister, trusting to the simple God-fearing folk of the country who wouldn't dare to raise any objection to the teaching of their master, nevermind it isn't his teaching.
The real error of progressive taxation is its unequal treatment of people under the law, which makes the law an ass. Time to end it.
The price of American citizenship should be the same for everyone.