Western rationalism no longer understands myths and their importance. Although almost all historic cultures valued myths, we are the obvious exception. Western culture has replaced these effective and healing story lines with ineffective, cruel, and disorienting narratives like communism, fascism, terrorism, capitalism, and consumerism. Each in its own way is a watertight explanation and refuses any outside critique.
Each human has a de facto worldview that determines what is important and what is not important to us, and we largely operate unconsciously--until we are awakened from our sleep. Worldviews usually have a symbolic story to hold them together, such as that of "Honest Abe" chopping wood in Kentucky and educating himself in Illinois. Clever "myths" like this become a standing and effective metaphor for the American worldview of self-determination, hard work, and achievement. Whether they are exact historical truth is not even important. We want and need them to be true. And that is okay.
Such myths proceed from the deep and collective unconscious of humanity. Our myths are stories or images that are not always true in particular but entirely true in general. They are usually not historical fact, but invariably they are spiritual genius. They hold life and death, the explainable and the unexplainable together as one. They hold together the paradoxes that the rational mind cannot process by itself. Myths, as do good poems and art, make unclear and confused emotions brilliantly clear and even life changing.
Myths are true basically because they work! A sacred myth keeps a people healthy, happy, and whole--even inside their pain. They give deep meaning and pull us into "deep time," which encompasses all time, past and future, geological and chronological, and not just our little time or culture. Such stories are the very food of the soul. When we start fairy tales with lines like "Long ago, in a faraway land" we are reaching for deep time truth. We Catholics used to say at the end of our Latin prayers, Per omnia saecula saeculorum, loosely translated as "through all the ages of ages." Somehow deep time orients the psyche, gives ultimate perspective, realigns us, grounds us, and thus heals us.
We belong to a Mystery far grander than our little selves and our little time. Great storytellers and spiritual teachers always know this. The postmodern world has rejected most myths except two, and these are especially lethal for the soul and for the poor and for the future: "I produce therefore I am" and "I consume therefore I am." This will never work for the soul, but we--believers and clergy included--have drunk this fairly new version of Kool-Aid.
Remember, the opposite of rational is not necessarily irrational, but it can also be transrational or bigger than the rational mind can process. Things like love, death, suffering, God, and infinity are transrational experiences. Both myth and mature religion understand this. The transrational has the capacity to keep us inside an open system and a larger horizon so that the soul, the heart, and the mind do not close down inside of small and suffering times.
The merely rational mind is dualistic and divides the field of the moment between what it can presently understand and what it deems "wrong" or untrue. Because the rational mind cannot process love or suffering, for example, it tends to avoid them, deny them, or blame somebody for them, when in fact they are the greatest spiritual teachers of all, if we but allow them. Our loss of mythic consciousness has not served the last few centuries well and has overseen the growth of rigid fundamentalism in all the world religions. Now we get trapped in destructive and "invisible" myths because we do not have the eyes to see how the great healing myths like the Exodus, Cross and Resurrection, Krishna and Arjuna in the chariot, and Buddha under the Bodhi Tree function and transform. 
In closing, let me offer this wish from Jungian analyst Clarissa Pinkola Estés: "I hope you will go out and let stories, that is life, happen to you, and that you will work with these stories from your life . . . water them with your blood and tears and your laughter till they bloom, till you yourself burst into bloom."