Christ the Eternal Tao is a book which teaches that the precepts of Taoism (which pre-dates Jesus' birth) foreshadow the coming of Christ, the Messiah, Who is Jesus. It is not a book which sets out to say that a Christian can learn about "the Truth" from Taoism (the author would not be happy with this sort of conclusion). What the book sets out to do is to show those who are Taoists, or who dabble in Eastern Mysticism, that the truth they seek in these religions is more fully revealed in Christianity, and in Christ Himself.
It is specifically a missionary tool for those Westerners who had left behind mainly Protestant or Evangelical churches to pursue Eastern religions (the author grew up in California, where such cults are popular), pointing out that the Truth they seek is in Jesus Christ - just not perhaps the Jesus Christ they were taught about in their previous churches.
God in His mercy would not abandon the millions of people who lived without the Law (Torah); the author of Christ the Eternal Tao shows that what is foreshadowed in the Torah, for the Jews, is also foreshadowed in Taoism for the Gentiles of the East. Obviously, now that Jesus Christ came and trampled down death through His own death it is time for those in these "old" religions to enter into the fullness of the Truth. That is what the book tries to do. In that respect its methods are no different to the Apostle Paul's when he preached to the Gentile pagans (i.e. acknowledging the truth in their own religion, and using it to point towards the fulfillment of their truth-seeking: Jesus Christ).
Christ being "the Way".
Tao in Chinese, simply means "the Way", and Taoism is the ancient religion of devotion to "the Way". The book simply seeks to point out to Taoists that "the Way" they seek to worship is Jesus Christ, a living Person, and that therefore they must now seek to worship Him in truth and love.
I hope that those who wish to read this book come back with their own review.