Fine, fine, I'll play along.
Lambert tried to have Jeannot assassinate the Divine, then ordered Evangeline to murder the people the Divine had sent to investigate Paramond.
The "belief" that you hold up as his virtue is a fanatical zeal, it is the same sort of belief that inspires terrorists and witch-hunts. He is indeed an overt maniac, because he has some seriously twisted belief that he acts in accordance with.
If you ever can find two strands of evidence that even vaguely suggest that Lambert had any hand personally in directing that loony i'd love to see it.
And as for ordering the Knight Captain to do her duty? Well that was a tiring circumstance, Lambert even explained his reasoning for it. It would further rock the boat when it was just about dang near capsized already, A cure for tranquility would equate that the rite isn't infallible and thus the one surefire method of removing criminals and the weak from posing a threat goes out the window, it would be executions for those offenses instead, it would result in even more upheaval then the mere differences of a handful of mages.
He said it several times, he was concerned with stability, he put that over peoples lives even, its not a perspective many people can get behind i realize but when you manage the bulwark between magic and humanity, extremes occasionally come into play.
As for his personality, well i guess we can agree to disagree on that, to me he wasn't an extremist, not a moderate but he didn't have a fanatic zeal to do anything beyond preventing a second imperium.