I told myself I wouldn't touch this thread with a 10ft pole, yet here I am. :/
Pedophilia is a choice and people choose to commit acts of pedophilia because they love their sin. They hate God but want his gift of pleasure, so they look elsewhere for this gift of pleasure and steal it from God by twisting it.
Lots of assumptions there, and nearly all are wrong. I think we can safely dispense with the God talk without further comment (I would call that a point that's been refuted a thousand times, but that would be understating it), and it would be wise to look in exactly what motivates a pedophile and how much of this is deliberate and how much is compulsion without simply assuming the answers.
Pedophilia can only be considered a mental illness if alcoholism, drug addiction, homosexuality, adultery, etc... can also be considered mental illnesses.
Well, homosexuality definitely isn't. It was dropped from the DSM decades ago. Adultery is a social taboo, not a mental illness. And alcoholism and drug addiction are compulsive, habitual drug use to the point of psychological/physical dependence.
What the heck even is a "sexual orientation"?http://lmgtfy.com/?q=Sexual+orientation
There is only one way that God has given us the gift of sex and it is enjoyed only in marriage, outside of marriage sex is still physically enjoyable but it is an expression of your hatred and rebellion against God.
The institution of marriage is historically a pretty recent development as are the social taboo against sex outside of marriage. Obviously, people were boning before the Bible existed. Also, the "gift of sex" is most definitely enjoyed a variety of ways, not "only one way".
Not sure I understand your last question but the real isssue here is, assuming that you're an atheist by other posts of yours that I've read
A regular poster at atheist forums
being an atheist would seem to be a relatively safe assumption.
why is it wrong for pedophile to molest a child?
Because it's rape and rape is wrong in virtually any moral framework, including *gasp* secular morality. You know, stuff like the golden rule and the harm principle. But unlike our religious peers, atheists need not worry about the cosmic consequences of eating shellfish, masturbation, and desecration of holy crackers - potentially all at the same time. All of the good and none of the garbage - a very attractive offer. The only real downside is dealing with scowling from the devout. But these days, they scowl at everybody. One wonders if love of scowling is the main draw of religion and all this God stuff is just window dressing.