Power in Harry Potter
Horcruxes or the Deathly Hallows? The choice was anything but simple for Harry. It was a choice analogous to the choice to use or to destroy the ring of power. What Dumbledore had wanted was more or less clear, so trusting him would send Harry after horcruxes. But Harry knew now that Dumbledore had a past which he had been unwilling to share (trust to) Harry.
How do you handle power? Is it to be sought and used for your own benefit, or is it to be taken only with the outmost care and diligence?
For Voldemort and the Death Eaters that is a silly question. Power is meant to be wielded, otherwise it is wasted. Power means having the ability to get what you want when you want it. For Voldemort, it was a way to overcome death and to get "respect" that he had not gotten any other way. This is community committed to the principle of survival of the fittest. You either rule the pack by force, or you walk around with your tail between your legs.
One of the big surprises in book seven is the past of Albus Dumbledore. We learn in the book that his history included a desire for power and a scheming about how this might be done. While this might have been "for the greater good," it was a vain (both in the sense of proud and in the sense of worthless) pursuit. His scheming led, however indirectly, to the death of his sister and marked him for life.
Dumbledore becomes one then who shuns power. Many wondered why he never tried to become the Minister of Magic. Some, like Dolores Umbridge, assumed he was trying to take the position. But the reality was that Dumbledore feared what he might do in that position of power. When Harry tells Dumbledore in King's Cross that he would have been a great minister, Dumbledore responds (DH p. 718):
Would I? . . . I am not so sure. I had proven, as a very young man, that power was my weakness and my temptation. It is a curious thing, Harry, but perhaps those who are best suited to power are those who have never sought it.
Dumbledore's wisdom in this matter is evident by two incidents signficant to Harry. The first was when Dumbledore realized that James Potter, Harry's father, had not just any invisibility cloak, but THE invisibility cloak. One third of the Deathly Hallows. Dumbledore had to examine it, and it was in his possession on the night Voldemort killed Harry's parents. Likely having the cloak would have made no difference, but the question remains, particularly for Dumbledore knowing his own motives for wanting the cloak.
Second, Dumbledore kills himself, effectively, by putting on the ring that contained the resurrection stone. Voldemort had cursed the ring (similar to the poison protecting the locket) and while he continued to live with Snape's aid, Dumbledore's days were numbered. The black hand was a reminder that death was upon him and that soon he would die. This is the reason drinking the poison was an easy choice for Dumbledore. He was dying already. Power is frequently the weakness of the great. (I'm tempted to get on a soapbox about term limits for elected officials, but I'll let you work it out.)
So, Harry's choice in book seven (and at other times as well) is the choice to pursue power, or trust his friends. When Dobby dies while saving Harry, Ron, Hermione, Luna, and others, Harry realizes what he has to do. Even though he knows Voldemort has discovered the location of the elder wand. Even though Voldemort will get that wand which could make him nearly invincible, Harry chooses to pursue the horcruxes and not the Deathly Hallows. To take the path that Frodo takes, not the path to power but the path of sacrifice. The path that will require him to depend on Ron, Hermione, and, eventually, Neville instead of the path where he could be the next great wizard.
As believers, we are called to humility. Jesus is much more than an example and much more than a teacher, but He is both. His example is that we do not grasp for power and authority in this life. The least shall be greatest. The meek will inherit. We are sheep in the midst of wolves. And as Harry finally trusts Dumbledore, we must trust our great Teacher who calls us to die.