"The sword shall never leave your house"

Even though David was forgiven his sin, this prophecy was not revoked.  The lives and deaths of his sons and grandsons through numerous generations bore out the consequences of his sin, the division that David engendered by embracing adultery and murder rather than holiness.

We tend to embrace a sort of immature grace.  Since Christ has paid the price for our sins, when we repent and receive forgiveness we think that's the end of it, and seem surprised when the consequences of our own actions echo well beyond what we ever foresaw in the course of our self-focused choices.  Our sin will always have consequences.  The moral restrictions on our behavior are neither the sadistic whims of a controlling God nor the primitive superstitions of an unsophisticated people.  Certainly our moral code must change to take into account our technological savvy, but not in a way that discards what either was instilled within us or has developed through painful experience over the millenia of our existence.

When we choose sin, the consequences often extend beyond the immediate ones we consciously disregard.  They are more manifold than we dream, and often go on a long time, some for decades or even for generations.  Maybe we won't see most of our children wiped out in war, or see them fight against us - though I've seen skirmishes of other sorts.  But these consequences are not the end of the story.

And the reason that is so is because of God's forgiveness, perfected as this prophecy of Nathan's is fulfilled  in the piercing of Jesus' side.  The sword shall never leave David's house, for David's pierced descendant remains on the throne of grace for all eternity.  The sword shall never leave your house, yet it has become a sword of reconciliation and boundless grace.

So let us choose to die to our desires with him, to have our own selfish will put to death by the sword.  And when we fail, let the blood and water of the pierced one wash us clean and restore us, and allow his grace to carry us and our loved ones through the painful consequences that may ensue.