I think liberals tend to believe first that people are fundamentally good...they reject the Judeo-Christian concept of original sin (and absolutely reject the concept of total depravity, save for their belief that conservatives are depraved). Since they believe that people are all good, they project huge amounts of trust into relationships and toward those they hold in esteem: liberal leaders.
Secondly, liberals have long ago denied the existence of an omnipotent, omniscient and omnipresent God, especially the God of the Bible Who has high moral expectations. Liberals are almost absolutely amoral, a trait shared, to some degree, by libertarians (who tend to be non-gullible, haters of big government, with very tight wallets).
But liberals, though they reject God, still long for some entity that is all powerful, all knowing and all present. Thus they assign God's attributes to government, expecting that miracles can be achieved with biblical grandeur and scope from the state. And with incredible gullibility they trust the liberals they want to be elected to produce godless miracles.
They expect the government to heal the sick (through socialized medicine), to raise the dead (by curing all disease and rolling back aging), to feed the hungry (while perfecting ethanol), to stop crime (by shooting guns out of criminal's hands), and to eliminate war (with "surgical strikes" that never cause collateral damage). They want to reduce the influence of the church while growing the size of government, believing liberal politicians possess messianic qualities. And they absolutely have blind faith in the liberals they nominate for president.
Gullible liberals worship the religion of state.
Sowell analyzes this in “Conflict of Visions”.
I’ll add the religious aspect to it.
If you view humans as fallen sinners, you will not trust them with too much power, because they are both incapable of using it as wisely as the individual over whom they rule, and they are prone to abusing that power.
The leftist view of humans (evolutionary thinking) is that humans are perfectable, and therefore, some are more perfect than others, more capable of making decisions for others than the individuals themselves. Perfection can be achieved by putting the right people in power with enough power to implement their vision.