Can the federal government’s spending spree last forever? Of course not. Even when economic growth is strong (hardly the case now, of course), it’s foolish to keep spending more than we take in. Congress is going to have to make some serious cuts. Otherwise, we’ll face a day of serious financial reckoning – and sooner than we think.

But you know the charge common sense like that opens you up to from some on the Left: You’re heartless. You’ll gut the social safety net. Toss poor people and seniors onto the street. “They don’t want to make Medicare sustainable,” writes New York Times columnist Paul Krugman, “they want to destroy it under the guise of saving it.”

According to this playbook, it’s immoral to suggest restraining the growth of entitlement programs.

Or is it? A recent exchange of letters between Archbishop Timothy Dolan of New York and House Budget Committee Chairman Paul Ryan (R-Wisc.) sheds a very different light on the matter.

His committee’s proposed 2012 budget “is not just about numbers,” Ryan wrote the Catholic prelate, “but about the character and common good of the American people.” Indeed, he said, it takes into accounts the Church’s social teaching regarding the poor.

Who, after all, will suffer the most if government spending continues to soar unabated? “The weakest will be hit three times over,” Ryan wrote, “by rising costs, by drastic cuts to programs they rely on, and by the collapse of individual support for charities that help the hungry, the homeless, the sick, refugees and others in need.”

Look at what’s happening in many European nations. They’re weathering financial crises brought on by years of overspending. So they’re being forced to make “drastic cuts in benefits to the retired, the sick, the poor, and millions of public employees,” Ryan noted.

What irony. If we take the Left’s proposed tack – cosmetic cuts, no real reform of entitlement programs – seniors and the poor will take a real hit down the road.

But the committee’s budget, Ryan wrote, “better targets assistance to those in need, repairs the social safety net, and fulfills the mission of health and retirement security for all Americans.”

Yes, some groups would see their welfare end – “entrenched corporations, the wealthiest Americans,” according to Ryan. Without that the kind of reform, our ballooning federal budget will never get out of the red.

In his reply, Archbishop Dolan didn’t endorse or criticize the budget, of course. But he did thank Ryan for recognizing an often-overlooked truth: Budgets are also moral documents. The values that helped shape our founding continue to affect our policy decisions, even if we are not always conscious of their influence.

Which values? A moral budget requires “fiscal responsibility; sensitivity to the foundational role of the family; the primacy of the dignity of the human person and the protection of all human life,” the archbishop wrote, along with “a concrete solicitude for the poor and the vulnerable.”

It seems paradoxical, but the way to save programs that helps seniors and those in poverty is not to just keep throwing more money at them. If they’re to survive, serious reform is in order. We need to greatly reduce waste, fraud and abuse, and ensure we’re getting help to people who actually need it.

That’s the fiscally responsible thing to do – and the moral thing.