The sad thing is, he's been convinced that a rather bad lie is what his entire raison d'être rests upon. His hope of eternal life, his very reason for living, and actually more than that his reason to believe he's got any value at all. So we come along and shake that foundation. We shake it, and he knows he's wrong. He can't argue against us, so he perceives us as a threat to all that is good because we threaten the lie upon which his reality is based. So, as an all too human response, he makes up more lies to justify his position. We're liars. We're sinful and bad people. Science is a conspiracy to undermine God. Scientists are devil worshippers. It's insane, of course, but I can almost understand it if we look upon it as a psychological illness. And yes, I do consider fanaticism just that. A psychological illness closely related with narcissism.
If we succeed in throwing down his rotten, corrupt basis I have little doubt he'll go through a phase of depression, he might reject God at least for a while. And he might become bitter. Natural responses to having illusions to which one adheres with fanatic fervor torn asunder. Still. I do not want that for him. No more than I want him to continue trying (subconsciously, no doubt) deceiving himself and others.