Though I'm sure you already know what Jesus talked about, we can go through it if you'd like.
The context of the Gospels often seems to depend on the tension between Jesus and the Pharisees, whose concern for rules and forms caused them to miss the real point of God's message. Jesus tried again and again to set them straight ... Confess and repent. Love God and your neighbor. Care for the poor, widows, and orphans. Become "obedient to death even death on a cross!"
The author of this wretched screed sounds exactly like a Pharisee. "Yeah," he seems to say, "all of Rowling's good guys exhibit the Christian virtues of love, self-sacrifice, servanthood, care for the opressed, etc. And all of her bad guys are servants of evil. BUT...."
And with that begins the rant above, which more than anything else shows O'Brien is more beholden to his theology than in reading the message Rowling is really sending.
O'Brien seems to have forgotten this little nugget:
Master," said John, "we saw a man driving out demons in your name and we tried to stop him, because he is not one of us." "Do not stop him," Jesus said, "for whoever is not against you is for you." (Luke 9:49-50)
Absolutely. Lets go through it.
John 15:18-23
18 "If the world hates you, you know that it hated Me before it hated you. 19 If you were of the world, the world would love its own. Yet because you are not of the world, but I chose you out of the world, therefore the world hates you. 20 Remember the word that I said to you, 'A servant is not greater than his master.' If they persecuted Me, they will also persecute you. If they kept My word, they will keep yours also. 21 But all these things they will do to you for My name's sake, because they do not know Him who sent Me. 22 If I had not come and spoken to them, they would have no sin, but now they have no excuse for their sin. 23 He who hates Me hates My Father also.
Matthew 10:34
34 Do not think that I came to bring peace on earth. I did not come to bring peace but a sword.
Matthew 5:13-16
13 "You are the salt of the earth; but if the salt loses its flavor, how shall it be seasoned? It is then good for nothing but to be thrown out and trampled underfoot by men. 14 You are the light of the world. A city that is set on a hill cannot be hidden. 15 Nor do they light a lamp and put it under a basket, but on a lampstand, and it gives light to all who are in the house. 16 Let your light so shine before men, that they may see your good works and glorify your Father in heaven.
2 Timothy 4:2-5
2 Preach the word! Be ready in season and out of season. Convince, rebuke, exhort, with all longsuffering and teaching. 3 For the time will come when they will not endure sound doctrine, but according to their own desires, because they have itching ears, they will heap up for themselves teachers; 4 and they will turn their ears away from the truth, and be turned aside to fables. 5 But you be watchful in all things, endure afflictions, do the work of an evangelist, fulfill your ministry.
Mark 16:15
15 And He said to them, "Go into all the world and preach the gospel to every creature.
So, as we can see from the previous Scripture, Jesus said that those who believe in Him and follow Him would be hated, He repeatedly commanded those who know Him to be the salt of the earth, to preach the gospel to the world, to keep telling people about Him and what He did on the cross even when they don't want to hear it, and He said that He came to "bring a sword", not peace. While He commands individuals to love their enemies, to care for the poor, etc., by no stretch of the imagination does that mean that Christians are to remain silent in the face of that which could be seen as another skirmish in the culture war.
So if there are people, including JK Rowling, who get offended by the fact that some Christians criticize her work based on their Scriptual beliefs, rest assured that Jesus said that that kind of thing would happen and it comes as no surprise when those who call themselves "Christians" lash out at those who have the gall to present an opinion that calls into question the aforementioned claim of "Christianity."
The fact that Ms. Rowling referred to her critics as the "religious right" reveals much more about her than it does about those for whom she holds so much contempt. It's quite revealing, actually.