Given the Sermon on the Mount and most of what we think we know about the life of Jesus of Nazareth, one would think that all true Christians would be liberals, or progressives, or at the very least, spiritually, Democrats.

They aren't.

Why?

The best answers I've read lately (and I just finished a guided reading of the Old and New Testaments) comes from Jonathan Haidt, The Righteous Mind: Why Good People Are Divided by Politics and Religion (New York: Pantheon Books, 2012).

Haidt's an experimental psychologist whose life and work have been devoted to understanding how and why people make decisions about what's right and wrong . . . and how they explain those decisions to others and to themselves.

He makes a convincing case that people all over the world are more or less hard wired by their DNA into certain ethical predispositions. That doesn't mean they are bound and determined to think and act in specific ways, but only that their natural inclinations are to lean in those directions.

Sometimes, though more rarely than we might expect, those inclinations can be changed. Haidt compares reason's efforts to affect our natural ethical instincts to driving an elephant with a mind of its own.

Most of the time the elephant wins, and reason's job is reduced to making up stories about why that was the direction we wanted to go in the first place.

In The Righteous Mind he cites convincing experimental evidence that we nearly always make decisions about what's right and wrong well before we start thinking about them, much less explaining to ourselves (and to others) why we made those decisions.

The stories we tell ourselves and others about those decisions, he continues, then confirm and reinforce our own behavior, and that of the people we in turn affect.

Because the vast majority of human beings act in this way (psychopaths, for example, don't), he argues, we have survived and thrived as a species of highly developed social animals.

Liberals, Haidt has discovered, are disproportionately driven by two of what one could describe as the six double-sided pillars of ethical decision making: justice and injustice; harm and mitigation of harm.

Self-identified liberals' ethical decisions, the laws they want to pass, and the stories they tell about why they want to do those things are nearly always disproportionately driven by those two double-sided considerations.

Conservatives are also driven by those things. They really do care, deeply, about justice and harm.

But they are also driven by at least four more considerations that liberals don't handle very well: group loyalty, respect for authority, an instinctive sense of awe (or disgust), and a profound reverence for what they describe as liberty.

Liberals, as a rule, just don't understand why conservatives aren't totally convinced they are wrong about something important to those of us on the left when we make an air-tight and perfectly logical case that justice and mitigating harm are unquestionably served by whatever it is we have done or want to do.

We forget that for conservatives loyalty, respect, liberty and a sense of reverence are just as important, not to mention certain innate reactions to things they see as disgusting.

Hence the appeal of religion to conservatives . . . the broad appeal of conservative arguments . . . and the difficulty liberals have in convincing conservatives that we are good and ethical people too.

Though conservatives tend to be true believers in a variety of religious faiths, in a larger sense it makes no difference whether this or that religious dogma is objectively true.

What counts is the religion's role in identifying and reinforcing ethical decision making and ethical behavior, not when it comes to mitigating harm or fighting injustice, but in all six areas.

Religion also serves an innate human need for belonging.

When it works for good, religion is magnificent.

When it's not insisting that one believe and act on clearly irrational and sometimes evil principles, it is unquestionably a force for good. When it doesn't, it can be shameful, or worse.

Liberals, to their detriment, just don't seem to understand the better angels of our conservative fellow citizens, especially those who are religious, or if we do, we don't communicate it very well.

Take this passage from one of the most famous left-wing people in history:

"Religious suffering is, at one and the same time, the expression of real suffering and a protest against real suffering. Religion is the sigh of the oppressed creature, the heart of a heartless world, and the soul of soulless conditions."

Beautiful, is it not?

And a classic example of Haidt's points about liberals' unerring focus on insuring justice and mitigating harm.

The next line in that paragraph about religion? "It is the opium of the people."

The quote belongs to Karl Marx.

Not a phrase designed to win friends or influence Christians. . . but, irony of irony, a phrase many of them would happily apply to religions different from their own.

Liberals need to do a better job of both understanding and speaking to religion and religious people. In many if not most areas we are on the same side.

And when it comes to reason, the better angels of our natures don't necessarily need wings to fly.