Conservatives/most Americans and especially Christian conservatives find it hard to comprehend how and why liberals lie so easily. Many liberals seem to lie without the slightest guilt or compunction.
For left-wing politics, lying goes back to the Russian Bolsheviks or earlier. The masses were lied to because the ruling elite (or the ruling elite to be) felt that the ends (Marxism) justified any means, and the masses were too stupid and ignorant to know what was good for them. But the ruling elite knew exactly what was good for them. Leftists have a rather low opinion of the masses, the average citizen.