According to the New York Times a US to professor, Susan Hamill, has suggested

that 18 US states seriously violate biblical principles in the way they tax and spend. She calls Alabama, Florida, Louisiana, Nevada, South Dakota, Texas "the sinful six" because they require the poor to pay a much larger share of their income than the rich while doing little to help the poor improve their lot.

The worst violator, in her view, is her own state of Alabama, which taxes its poor more than twice as heavily as its rich, while holding a tight rein on education spending.

The poorest fifth of Alabama families, with incomes under $13,000, pay state and local taxes that take almost 11 cents out of each dollar. The richest 1 percent, who make $229,000 or more, pay less than 4 cents out of each dollar they earn, according to Citizens for Tax Justice, an advocacy group whose numbers are generally considered trustworthy even by many of its opponents.

In her new book As Certain as Death Hamill argues that:

The Bible commands that the law promote justice because human beings are not good enough to promote justice individually on their own. To assume that voluntary charity will raise enough revenues to meet this standard is to deny the sin of greed.

I agree, and did so in an article written a while back now called the Theology of Taxation.

Those who argue otherwise do two things. First they assume God created individuals in isolation. That is clearly not true. Second they assume that humans aren't the agents for the fulfilment of God's will on earth. Again, I can see no evidence for that.

Progressive taxation is, in my opinion, not just consistent with Christian teaching, it is a requirement of Christian teaching.