"This is the most perfect, imperfect organization... It has to be the truth."
This is of course a completely illogical statement. The conclusion in no way follows from the premise, which is itself flawed.
As intelligent a person as your father maybe, he clearly succumbs to stubbornly holding on to his beliefs when anything threatens them.
Although it probably will not help him see TTATT, you might find this book enlightening as to why otherwise smart people refuse to accept obvious truth: