I think maybe Daoism and Confucianism confuse us because they deal with some of the same questions as Christianity does in Europe: especially man's place relative to the whole cosmos, and universal rules for behavior. Very little that I have read (in
Analects or
Dao De Jing) mentions God, a god, or the gods, so while they may refer to spiritual matters, the focus is not the spirit as it relates to God. Now Daoism in particular seems steeped in the earlier language of Buddhism, which in turn gets much of its language and notions of absolute reality from the Hindu Upanishads. So if you really stretched, you might be able to claim that the "oneness" of Daoism is the Brahman of Hinduism. Some westerners seemed to have associated it with God in any case, but I don't think there is enough there to make this claim with any certainty and it would still be an Upanishadic version of God, of which we are all by nature part. Daoism also relates itself the Chinese pantheon (supposedly) though I do not know if that is in such a way as to make it more religious than, say, any Medieval philosopher in Europe who might incorporate God into his philosophy.
Some sources:
Analects of Confucius:
http://afpc.asso.fr/wengu/wg/wengu.php?l=Lunyu
Dao De Jing:
http://www.yellowbridge.com/onlinelit/daodejing01.php
Upanishads:
http://www.sacred-texts.com/hin/upan/index.htm
We also have to get around two kinds of translations: language translation and cultural translation. By the second I mean the way we use the context of our culture to interpret the translations we have already made into our own language, or that we use in the first place to help in our language translation. Wikipedia's
Dao De Jing article mentions the word "trinity" in the context of Christianity, but there would be no reason to make this connection from the Chinese perspective. Particularly egregious is the relation in popular Western thought of
yang with "Good" and
yin with "Evil" which leads some to conclude that Chinese philosophy "preaches" harmony between the two. The two are psycho-physical notions (physical properties of the world that are believed to have analogues or direct presence in the mind.)
There is of course the common idea (at least among some modern folks) that
Dao (literally "Way") is "way" in "I am the way, the truth, and the life," but connecting the two is fraught with difficulties. One might say that Jesus was pre-figuring himself for an eventual dialog with the Chinese, but that is even so not a pointer that Daoism is religion, but a statement that some want Christianity to encompass Daoism.
Tuke's mention of Universal Natural Law is right on the mark. Both Chinese philosophies were heavily concerned with the notion that a single law that could be expressed in physical terms (
Yang and
yin for example are older Chinese words for sun or daylight and moon or nighttime) also effect human beings and controlled how they function spiritually and socially. Lewis believes that this is the same Natural Law that Paul refers to, though Paul, Lewis, and Lao Tzu may have different theories about how this Law functions. If I were to speak in very broad terms, I would say that Christianity and Hinduism express Natural Law ideas in terms of laws of momentum (the Physics term "momentum" is the best translation of Sanskrit
karma as it is used in Hinduism) and Daoism expresses the Law in terms of Thermodynamics (
Yang and
yin are relative extremes of high energy and low energy that cannot cause change except through interaction). Christianity has at times divested itself of physical notions in favor of "spiritual" ones, but has always remained concerned with chains of causation, even in the spiritual realm.
Sentio ergo est.