Don't take things at face value
A common theme emerges in Chapters 15-18, where friends are taken for foes. Fighting ensues frequently between the pilgrims and "monsters," the latter of which turn out to be converts of Kuan-yin sent to help the very pilgrims with whom they are in conflict. This is explained by the fact that the pilgrims, usually Monkey, made no mention of their mission or scripture seeking. Once help is sought from Heaven, the misunderstandings are explained and the pilgrims continue on their way, slightly richer in items or spirit for their trouble.
Satirizing of government
Most scholars agree that the author's portrayal of Heaven and its ruler, the Jade Emperor, is a satire on the secular, earthly government below. The Jade Emperor is heavily satirized as a despotic, rather irrational leader surrounded by petty ministers and bureaucrats. His carefully balanced hierarchy is meant to mirror that of the actual Chinese government. Monkey experiences the unfortunate comic nature of this government when he is made a glorified stable boy, and then given an empty and powerless but beautiful title, in attempt to appease him. This leads Monkey to conclude that he could do a better job than the Jade Emperor, and marks the start of all the trouble he causes in Heaven.
Live frugally
One of the central tenets of Buddhism and of this novel is to be happy with what you have and live frugally. Each of the main characters found themselves further from Heaven when they reached beyond their station or power. A good example of this is Monkey, who tried to replace the Jade Emperor himself. Because he could not be content to lead his own monkeys, Monkey fell onto harder times as he was imprisoned by Buddha and then forced into a pilgrimage with Tripitaka.
Redemption
Tying into a religious tenet again, this next theme professes the idea that it is never too late for redemption. It doesn't matter what a person has done, or how evil their deeds have been, they can be saved if they turn towards doing good and seek enlightenment. This idea is seen time and again throughout the novel, and is especially present in the redemption of each of Tripitaka's disciples.
Perseverance and Faith
It is only through the determination and will power of the four disciples that they are able to overcome the challenges that face them. Several times, Tripitaka is in despair over their situation, only to be brought back to hope, usually by Monkey. The teamwork and cooperation that allows the pilgrims to surmount all odds would be useless if they did not continue and hold true to their faith.
Death as a fluid entity
Throughout this novel, death or the threat of Yama, King of Death, is often present and an impetus for the plot of the story. Fear of death and mortality is the very reason why Monkey begins his quest for immortality, so that he may rule his monkey subjects forever, not just for a few hundred years more. He is able to circumvent his death and that of all of his monkeys by wiping their names out of the Register of Death.
This idea of death as fluid and changeable returns in Chapter 11, when it is discovered that Liu and Blue Lotus (both of whom recently committed suicide) were actually supposed to live to a ripe old age. To remedy this mistake, Yama sends the two back, and decides to place Blue Lotus in the body of Jade Bud, the emperor's sister who is due to die soon, as Lotus' old body was dead too long to be of any use to her now.
The truth will emerge
Throughout the novel, there are many disguises and deceptions employed by everyone from monsters to Monkey. Nevertheless, these lies never last long, and the truth inevitably surfaces. One notable example of this lies in the tale of the false king, and his eventual exposure after three years. Another instance of this is portrayed in the defeat of the three false Immortals: Tiger, Ram, and Deer.
