Yeesh! Lighten up, people!
Some Christians view everything in the world through the distorting lenses of their faith and the Bible, and to them, anything that is not obsessed with them is wrong. The fact is, there is nothing "anti-Christian" in the RJ novels, any more than in The Lord of the Rings, the Dune cycle, or, for that matter, Narnia, which for all its allegorical content has no actual Christianity in its makeup. The mythos of the Adversary Cycle and the RJ books may not include Christianity, but that does not make it ipso-facto anti-Christian. The mindset that finds anything not specifically Christian to be anti-christian is the same mindset that used to ban any fiction at all because it wasn't "true". These folks would have no entertainment except Biblical entertainment and are likely the same kooks who would burn Tom Sawyer and The Catcher in the Rye.
But then, people with axes to grind will always find some grist to their hate mills. I don't see anything at all homophobic in the RJ books either, but then, just as there are those who see anti-christianity everywhere, there are those who see homophobia everywhere too. As for being anti-Semitic, well, that is laughable: maybe some people see Abe, as Jackie Mason would say, as "too Jewish", but I have known folks precisely like him. And as for being anti-Arab, well, there is a difference between having characters who with anti-Arab sentiments and being anti-Arab oneself.