The mind is an assortment of ideas. One would typically not reveal everything that is on one's mind. If the running commentary that the mind generates is spoken aloud in its raw form, it can turn out to be blatantly humiliating or infuriating. Such simple-mindedness is usually not rewarding.
The initial simplicity and truthfulness of the leading character in the movie depicts him as a lame loser. Then one day, he fabricates a lie in pursuit of a selfish gain. He is surprised at the success he earns spontaneously. That's when he realizes how much he can conquer with some intelligent twists of his words and gestures.
“A lie is a deliberate deviation from the truth.” Generally, one resorts to lying to secure selfish gains. Lies can also help in dodging punishment and humiliation. However, sometimes ‘good’ lies can be sweetly helpful. For instance, while the stark truth about the unattractiveness of a person can be demeaning for a person's self esteem, a few kind words can boost one's morale.
The movie depicts the common man to believe that after life, there will be no more than an 'eternity of nothingness'. Then it sprays hope amidst people enticing them to fetch for the reward at the end of this worldly life: the 'mansion' that people would get for their good deeds. People are fascinated with the notion that there is something more to life post-life. Then, it makes a reference to the 'Man in the Sky' who has a bigger plan for us all. In this way, the film also delicately touches upon what several religions across the world hold in variant versions.