Reason for the founding of CaoDai:

Each time that human beings suffered when societies became chaotic, a religion was founded.  For millenia, human beings have been blessed by having many forms of religion such as Hinduism, Judaism, Zoroasterianism, Buddhism, Taoism, Confucianism, Christianity, Islam, et cetera. One always observes one same truth through religions, even when they are so physically different and founded at different times and places.

The truth is the existence of a Creator of all the universe and living beings, the existence of the Supreme Being who reigns in everyone's heart.  Religions have called this Supreme Being by different names: Macrocosm by Hinduism, Yahweh by Judaism, Ahura Mazda by Zoroasterianism, Tao by Taoism, Monad by Confucianism, Allah by Islam, or simply "God" by a myriad of English speaking religious persons.

Then with time, the truth gets corrupted and diluted.  Human beings have a tendency toward materialism.  They discriminate against each other because of physical differences between religions; they fight, and kill each other under the form of religious wars; the relationship between parents and children,
husband and wife, brothers and sisters, friends, becomes controlled by material desires and money.  Universal philosophies such as Baha'i, Theosophy, and Oomoto Foundation were created, trying to connect the Eastern and Western religions.

In 1926 the Supreme Being founded CaoDai in Vietnam to show people that all religions are indeed of one same origin.  In 1926, the Supreme Being gave the following message:

Nhien Dang Co Phat (Dipankara, an old time Buddha) is Me,
Sakya Muni is Me,
Thai Thuong Nguon Thi (an old time Immortal) is Me,
Who is Cao Dai.

In founding CaoDai, the Supreme Being teaches man to realize that all religions have one same origin, and not to discriminate against each other but to love each other as
brother and sister, to cultivate self to find God in one's heart.

The oneness of God, Man and the Universe.

In CaoDai text, among many teachings, one stands out: The sky, the earth and ten thousand things are of one same constitution.  (Thien Dia Van Vat Dong Nhat The.)   ("Ten thousands things" symbolically means the multitude of diverse forms of matter in the universe.)  A stunning assertion, but what does it really mean?   What does it imply?  In this universe, all things share atoms, but a few situations would show how the sky, the earth and all the things in the universe can be of one
same nature.

A pedestrian and his dog walk wearily in the heat, sweating all over, looking for a respite, shade, water.  A plant by the road wilts under the same fierce sun.   Water would be the savior for the man, the dog, and the plant.  Without water, under the heat, man, animal, and plant would be dehydrated, die and decompose into earth elements.  It appears that the stone is untouched but if the stone bakes at hight enough temperature, it would also become dehydrated and decompose.

Thus the same effect from excessive heat is observed for the man, the animal, the plant and eventually the stone.  If they don't have the same basic constitution, how is it that a common result occurs?

Regarding another aspect of life, a common law governs reproduction.  A marigold plant gives seeds which if placed in appropriate conditions will produce marigold plants.   A dog, after conceiving, will give birth to a dog.  A similar law applies to the human being.  The same rule of specific continuation of the line applies, whether human, or animal, or plant.  This common law of physical existence is reminiscent of this saying from ancient China:

Ta cung muon vat dong sinh;
Ta va muon vat su tinh chang hai.

Myself and ten thousand things are born together;
Myself and ten thousand things bear together the same condition.

How about the universe?  Ten thousand things on this earth are part of the universe and of its smooth functioning.  Lives on this earth rely on the sun, and on the punctuality of the earth evolving around the sun so that they receive the narrow range of light and temperature needed.

Physical bodies of all lives on earth are part of the body and life of the universe.   After death physical bodies turn to dust, also a part of the universe.

As to the emotional part of human nature,  day-to-day life, with its wheel of fortune's ups and downs,  normally causes the same feeling among all mortals.   In the theater in session, most people watching the play laugh and cry at the same instant.

As to the spiritual, God has granted mortals and everything in the cosmos a part of His spirit.

And among humans the spirit is shared, which is why they have similar basic principles and the same conscience.   This is why the world's great wisdom traditions have a common central essence and why, for example, the motto on the U.S dollar bill, E Pluribus Unum, would have a counterpart in Vietnamese:

Nhut Bon Tan Van Thu;
Van Thu Qui Nhut Bon.

From one, emanate many;
From many, emanates one.

Many times during this manifestation, the Supreme Being taught:  "I, your Master, am you; you, My children are Me;" or "I divided My spirit to create materials, plants, animals, and humans; I am the father of all lives; where there is life, there is Me."  This teaching constitutes the most important principle of CaoDai and becomes the ultimate goal of all mortals on this earth: to become one with the Supreme Being.

CaoDai without being CaoDai is the true CaoDai.
Cao Dai gave the following message:

Dipankara Buddha (an old time Buddha) is Me,
Sakya Muni is Me,
Thai Thuong Nguon Thi (an old time Immortal, previous incarnation of Lao Tse) is Me,
Who is Cao Dai.

Various religions contain one primordial truth (which we call CaoDai).  If CaoDai religion is only CaoDai, a separate defined entity, it would not truly be CaoDai as it is meant to be.  If CaoDai is not only CaoDai, but encompasses Buddhism, or Taoism, or Confucianism, or Christianity, or any path toward God, it is then truly CaoDai.   CaoDai does not propound to convert the followers of any path, but wishes to unite all faiths in the understanding that faiths all are of one same principle, and teach tolerance between the religions.  That alone would put an end to the religious strife which leads to the majority of wars in the world.

What is the goal of the CaoDaist?

Love and justice for all constitute the immediate task of CaoDai.  The ultimate

goal is to help humankind achieve ultimate reunification with the Supreme Being through cultivation of the True Self.

On a practical field, CaoDai offers two ways of practice for self-cultivation:
the outer way or exoterism and the inner way, esoterism.  In exoterism, the adepts continue to lead a family life while devoting themselves to the practice of good and the avoidance of evil.  One of the ways to accomplish this is to abstain from destroying living beings or in other words to love living beings with a true love, an unconditional love and to observe justice (don't do to others what you don't want others to do to you).   In practicing exoterism, CaoDai serves the world with a sense of international sisterhood and brotherhood, in accordance with the Supreme Being's teaching.  Besides this, the adepts may perform at least one ceremony per day worshipping the Supreme Being at home, and twice a month at a local temple.  In general, most CaoDaists belong to the exoteric practice.  The principal temple of the exoteric form is called the Holy See, and is located in Tay Ninh, Vietnam.

Esoteric practice has, however, become more and more popular.  The esoterist aspires to unite with the Supreme Being by concentrating on self-cultivation by way of meditation and self-purification.  It is not necessary to enter a temple to practice this form of CaoDai, for the esoterist recognizes that the temple resides within.  But by coming together, esoterists can share, learn, firm up their thinking and practice together to further their personal self-culvitation.  They learn to simplify their needs, to become sincere, kind, loving persons.  They learn to expand their love to humanity and nature, to control and become free of adverse emotions in order to become one with the Universe and become closer and closer to oneness with the Supreme Being.   Esoterism was originally practiced by Ngo Van Chieu and the group that developed around him.  The main temple for esoterism is located at Can Tho, Vietnam in the Mekong Delta.

The Symbol of CaoDai:
God ordered to symbolize Him by an Eye, which is the image of the universal and individual consciousness.
God's messages:

The eye is the master of the heart;
Two sources of pure light (Yin and Yang) are the master;
Light is the spirit,
The spirit itself is God,
God is Me.