Authentication of the gospels is actually quite thorough. In the four gospels, some events are out of chronological order. Some are omitted in different gospels. Some things are explained a little differently. However, they never truly contradict. Not only is this consistent with different people writing different accounts (VERY hard to fake), and the perspectives given fit the known personalities of the credited authors. All evidence points to them being authentic.
I wouldn't rely on the book "Holy Blood/Holy Grail." If it's the book I think it is, both the National Geographic Channel and the History Channel investigated the claims of the book and found no credible evidence to back it. The fact is that all four gospels survived. A page may have been lost here or there, but I doubt it.
As far as the divinity of Christ, you might want to check out a book called "A Case for Christ," by Lee Strobel. The book examines the resurrection legally and concludes that it is the only logical explanation to account for what can be already be proven true. One of the most compelling bits of evidence is the deaths of the disciples themselves. One doesn't face a horrendous, torturous death like that of the disciples for something that isn't true, especially when denying it is a quick and easy way to get out of it.
There's no problem with things being questioned. It's when an age-old truth is suddenly assumed false by millions of people based on a bunch of phony evidence. If as many people who believe the premise of the Da Vinci Code believed that the holocaust was a giant hoax because of a small amount of flimsy evidence, would you still think it's good to question such things?