It’s Christmas season, the time for carols, family get-togethers, exchanging gifts, warm memories of childhood. Here in this great country, we have always been able do so in peace, the priceless benefit that we so easily take for granted.

Our favorite Christmas theme is “Peace on Earth,” but we know that much of the earth is not very peaceful right now. Ironically, we are celebrating the birth of Jesus on a silent night in the little town of Bethlehem — a place that is now in the heart of a war-torn Middle East.

This Christmas, we watch televised video of the unfolding horrors of the Israel/Hamas conflict in the comfort of home and from a safe distance. For a moment we sense the misery of the war’s victims, but when we’ve seen enough, we can turn away and get back to our pleasant holiday.

And in fact, for most Americans, that has been our life experience — war is an unpleasant and inconvenient but far-away problem. Post-Afghanistan and Iraq, few of us suffer war’s actual ravages. It all happens in distant lands, to people we don’t know. We can imagine it, but we don’t feel it.

The citizens who serve in our military forces, often in dangerous places, make it possible for the rest to remain home, safe and untouched. For their sacrifice and that of their loved ones, we must be eternally grateful. But with just a few exceptions, Americans only go to war — it doesn’t come to us.

And so, the obvious question: Why in this dangerous new world are we so fortunate? And, more importantly, how do we preserve that good fortune?

Our homeland is now readily accessible from all corners of the earth. The geographic buffer of vast oceans to the east and west no longer provides the isolation we once enjoyed. But even in a shrinking world, the recipe for avoiding war at home remains simple: (1) a superior military capability and the will to deploy it if needed, and (2) rigorous, relentless border security.

The Israel/Hamas conflict reinforces the importance of those simple principles, amplified once again by the horrifying dimension of unfettered terrorism.

The Hamas strategy was crystal clear: start with a sudden, large-scale, savage assault on unsuspecting Israeli civilians; showcase to the world the depths of your barbarity — torture, rape, slaughter of innocents; take hostages and retreat with them to your fortified enclave in neighboring Gaza, amidst and shielded by innocent Palestinian civilians; and dare your Israeli enemy to come after you.

It’s an inhuman strategy — and it’s working. Many in the world, and even here in the U.S., are outraged more by the human suffering resulting from the Israel Defense Forces’ aggressive response than by the barbaric Hamas attack that necessitated it.

The obvious lessons for all:

• The time to secure peace is before the war’s ignition, not after. Once the bloodshed begins and the casualties accumulate, the hostilities are more likely to spread than to be restrained.

• Warfare in populated areas produce far more innocent victims than combatant casualties.

• Defending one’s nation from a powerful enemy within — or, as in Israel’s case, just outside the doorstep — is enormously difficult.

To these points, imagine if Israel had managed to keep Hamas out of Gaza from the start. And for context, keep in mind the intense international pressure on Israel over the years to soften its defense posture, not stiffen it. Hindsight is always 20/20. In this case, it is clear that Israel’s reluctant tolerance of Hamas’s proximity enabled the catastrophe we’re watching today.

Which takes us full circle back to our U.S. homeland security challenges. What happened in Israel is a grim reminder of the risk posed by the flood of unvetted migrants entering our country every day.

Could an assault patterned on the Hamas strategy happen here? Absolutely. Roaming freely through our vast country, terrorists of the Hamas or ISIS ilk could establish a toehold, then a foothold, and from there launch a similarly devastating attack on Americans.

And regarding the politically tinged battle in Congress over funding to support Israel in its defense against Hamas vs. that needed for critical improvements to U.S. border security, anyone who believes those two needs are unrelated is sadly mistaken. Both are imperative, now.

And what else must we do to keep war from our shores? We must get our own house in order, such that hyper-partisanship does not handicap our ability to take the actions central to America’s security and survival. Abraham Lincoln figured that out a century and a half ago. “A house divided against itself cannot stand.”

Peace on Earth? A noble objective, but we’d better start right here.