To sue for libel or slander, what one must first do is prove that the statement made is false. The Courts have repeatedly held that they will not arbitrate between one theological position and another.
This is not a bad position. Europe has had countries that have had a state religion - or a state approved religion - e.g. Spain, with Catholicism, and Enland with the Church of Henry VIII. anyone familiar with the difficulties that arise when the Church (whichever one) starts to exert its influence in the realm of laws and/or politics to the extent that they have in Europe can understand the wisdom of the Courts in the US. Secularism will arise whether the State has a recognized Church or not (see, e.g. the current conditions in Spain). In the US, the dispute is between any Church and secularism, as to whether or not the Church has a legitimate voice in any event.
The next issue is proving damages. Since the Church’s position is that it is out to gain souls, not bodies, and since the Church’s position is that all must enter Heaven through Christ, but how that works is between God and the individual, and not determined soley on actual membership (sorry, that is a short-hand description of a sticky issue), it would be hard to prove that any damage occured, let alone the amount.
As to the Da Vinci Code, it was published as fiction and is protected speech. Jack Chick falls under the area of theological disputes, and even if it can be shown that he does not correctly state our teaching, it would be held that it is still a dispute over theology, and the Courts will not determine the correctness or lack thereof of theological positions. Again, how does one show damages, even if it is shown that Chick lied?