The tao is omnipresent. That means it is present throughout Taoism, but that it is equally present throughout Islam, Christianity, Judaism, Hinduism, Voodoo, Santeria, and every other religion.
The tao is completely areligious. If being a part of the tao was a religious experience or qualification, then every single person in the world would be a Taoist. Tao and Taoism, however, are not the same thing.
Taoism is a specific religious tradition and not everyone is a Taoist. So while the tao may or may not require deities, that has no bearing upon Taoism's requirement.
But how does Taoism require deities when the Dao De Jing doesn't seem to mention them?
In order to understand that, one has to first examine Taoism's historical development.
The Dao De Jing dates to the 6th - 2nd Centuries B.C. Taoism was established as a formal religion in the 2nd Century A.D. No matter where one places the Dao De Jing, it came into existence at least several centuries prior to Taoism's founding.
By the time Taoism came into existence, it relied upon a complex foundation of ideas and traditions, of which Laozi's philosophy was only a part. This foundation came to be captured within a "canon" or an officially sanctioned group of core religious texts.
The earliest versions of the canon contained many thousands of texts, of which the Dao De Jing was but one. The fact that one text within the canon may not contain a specific idea does not mean that the rest of Taoism does not hold that same idea to be valuable and necessary.
It is also questionable whether anyone can make a concrete case that the Dao De Jing doesn't consider deities.
There are several passages in the Dao De Jing that seem to imply recognition of deities. But even more important is the fact that Taoists often interpret the Dao De Jing in radically different manners than do standard Western translators.
Whereas Americans simply walk into a bookstore and purchase a copy of a translation, Taoists are traditionally taught an oral tradition of interpretation that has great religious and ritual importance. Taoists see deities in the Dao De Jing, while areligious Western translators often do not.
Taoism, from its very beginnings until today, incorporates deities. It doesn't, however, recognize a God in the Western sense. There is no great omnipotent being, external to man, who manages the universe. Such management is left to the tao, but the tao itself is not worshipped. Taoist deities are part of our universe, not separate from it, and are as equally beholden to the movements of the tao as are normal people. In that sense they are "deities" moreso than "Gods."
They are worshipped or venerated in Taoist temples. Without deities, there would be no need for temples! Taoist deities exist in a great pantheon. Within this pantheon is a structure, with various deities operating under the authority of other deities.
The pantheon generally changes over time, and various Taoist sects have differing views of it. But all Taoist sects acknowledge the pantheon's existence.
