why do xians lie?

Why is it that xians lie all the time. There is this guy called david robertson who wrote a book called the dakins letters (he has the nerve to charge for it but it is also free on the internet however i wont link to it because i wouldnt want to publisise it) Anyway, he pops up in Richard Dawkins website now and again lying all the time. Look at his posts

Here are some of his lies:

->he made up all the quotes on the back of his book recommending it
->he once paid a dud cheque to someone knowing it would go into his overdraft
->he said he is an xian then posted on a sunday
->he said richard dawkins commisioned a response to his book when richard dawkins only asked paul kirkby and no money was exchanged.
->he claims he never lies and that we have no evidence for these acusations

now why is it xians lie all the time? anyway, going on richard dawkins website has backfired on him as people have now gone and written bad reviews of his book on amazon and his publishers site