Does Pope Benedict also oppose the Twilight series because it glorifies creatures of darkness, stalking, abuse, Jacob's BD thing, racism, classism, ageism, etc....? 

Harry Potter does not blur the line between good and evil. It is made /very very/ obvious that Voldemort is BAD and Harry, while flawed and a relatively believable character, is GOOD. Harry is kind, despite his tendency to take out his troubles on other people; Harry is very loyal to his friends; Harry does not allow himself to be tempted by the allure of the Dark Arts. Voldy, on the other hand, is heartlessly cruel, even to his followers, even to the woman who serves him loyally and very obviously loves him; Voldy loves nothing and no one except himself; and Voldy is the most evil wizard in the world.

Sure, in the HP world there are grey areas. No one is perfect. Harry can be nasty, pig-headed, and rude. Harry is impulsive and he ignores the good advice of his friends on multiple occasions. He often lets his temper get the better of him (see him yelling at Dumbledore at the end of OotP). He's not afraid to use an Unforgivable Curse (in DH) in order to get what he needs. However, he has a good heart and he readily thinks of his friends' safety and happiness ahead of his own.

Take Dumbledore as another example. Dumbledore believes firmly in the power of good over evil; the power of a pure, whole soul over the power of a broken one, despite the broken soul's body being (relatively) immortal. Sure, Dumbledore planned to do what Voldy did - but his sister's death caused him to reform, immediately and completely. He's good now, even if he wasn't in his teen years.

If you're referencing the "there is no good and evil; there is only power, and those to weak to seek it" line, that was a VILLAIN saying that in justification for his actions, and he was later DEFEATED completely. In writer-speak, that's like saying "that's what that guy thought, but he was wrong." 

Now, about it "cutting off young reader's relationships with God" and "promoting secularism."

Harry Potter does nothing of the kind. I'm not particularly religious myself - I believe in God, I go to church, I pray, yeah, but at the moment I'm not entirely sure what I believe. I look at the church and I see an awful lot of browbeating going on (subtle browbeating is still browbeating). I think there is a God, but I'm not sure I want to be a part of the church (does that make any sense?). And I'm not sure if I'm comfortable with such a vindictive, judgmental God, either.

None of my opinions on God and religion have anything to do with my reading Harry Potter starting, um, when I was about nine or ten? When I was that age (and for some time afterwards) I was a very serious little religious thing. It was only later, after reading stuff like Les Mis, Wicked, and other books that actually discuss religion, God, and sort of thing, combined with my obvious naivete as a child (and my wonderings about it) that got me started in my more cynical views of God and religion (and science, and the government, and lots of other things really.)

I know I can speak only for myself, but Harry Potter had nothing to do with my religious life, thanks very much. Unless you want to argue that it's a subconscious catalyst or some such.

Now, promoting secularism. What? 

Secular is defined by the dictionary imp in my computer (tooo much Pratchett) as:

1 denoting attitudes, activities, or other things that have no religious or spiritual basis : secular buildings | secular moral theory. Contrasted with sacred .

2 Christian Church (of clergy) not subject to or bound by religious rule; not belonging to or living in a monastic or other order. Contrasted with regular . 

Um, yeah, so Harry Potter is secular. So are most other children's books. Heck, so are most adult books. HP has no spiritual basis; it's fantasy. It's FICTION. Neither does HP adhere to any religious rules, and by no stretch of the imagination does it belong to a monastery. If simply being secular means that it PROMOTES secularism, then, not only does HP promote secularism, then so do

-Sweeney Todd

-Phantom of the Opera

-Twilight (arguable. Twilight's got some pretty Mormon morals going on)

-Cricket Magazine

-1984

-Lord of the Rings

-Nightmare Before Christmas

-Eragon and the Inheritance series

-HG2tG

-Pretty much any nonfiction or fiction work that does not contain outright religious morals.