In reality, however the best way to guarantee increasing Christian isolation and diminished religious liberty is to flee the field, to leave the military to its more secular members. If Christianity becomes an aberration, rather than a mainstream part of military life, commanders will have little practical incentive to accommodate religious expression — particularly in the face of opposition.

But there’s a deeper reason why young Americans shouldn’t heed Mr. Huckabee’s advice: Leaving the defense of the nation and its liberties to secular citizens would constitute a profound moral failing, an abdication of faithful Americans’ duties as citizens. The blessings of American liberty — even when that liberty is under attack — are purchased for a price in blood that should and must be borne by every American community, including the community of faith.

Barack Obama is not America’s only inadequate commander-in-chief. Jimmy Carter, after all, brought the armed forces to the brink of ruin, and the presumptive presidential frontrunner — Hillary Clinton — shows no indication that she’ll change any of President Obama’s worst military policies.

Yet the nation still needs a defense.