Adam will make up a major piece of my book, but for not let me briefly explain Adam's importance and transgenderism. Adam was began as an androgyne - a person mystically both male and female. "Adam" literally can mean "humanity." Thus God says, "It is not good for humanity to be alone." When God makes Woman, God has taken the Female out of the first human and leaves only male. Thus the Man is only male by the end of the story. It is crucial that we understand the the "rib" motif is entirely fictious and unbiblical. The word in the text is never used to mean "rib" in any other context and Hebrew has a word for rib that is absent here. The word should be translated "side" or "part," the same way it is translated in every other verse. Thus "God took one of the man's sides and . . . made a woman from the side." If it is Adam's side, we must ask, "Which side was it? Adam's left side, right side, angry side, ambitious side, emotional side?" It was his female side.

There are many pieces of evidence lending credence to this interpretation:

1. Gen 5.1-2 says God created "Adam" male and female, with no mention of Eve.
2. The Babylonian Talmud says so explicitly. The Talmud is our earliest interpretation of Adam outside the Bible itself.
3. Genesis describes all of creation as an act of separating the One into the Two, especially opposites.  The Day and Night begin as One, then separated. The land and sea are one until God separates them. The sun, moon, and stars are all jumbled together until God creates them. Etc, etc. It is totally consistent for female and male to start as one unit and God creates their distinction out of their original unity in Adam.
   
4. Many mythical themes in the Bible are also found in other traditions. For example, a great flood, a virgin birth, and a dying god. Many people of many spheres (JRR Tolkien in mythology, CS Lewis in theology, Jung in psychology, Campbell in anthropology, etc) that all these themes point to a common origin (and Christians believe, some of them a common future event). Creation accounts in other cultures also include a first human as an androgyne. Eg, Plato.
5. Genesis says the mystic meaning of heterosexual marriage is that the two people who have a common origin (Adam). This makes some sense if the side God took from Adam was only random flesh although in the same chapter, Adam came from dust and humans have mystical drive to unite with the dust. The verses make more sense and is much more powerful if the context means that Man lost his female side and Woman her male side and they are driven to re-unite their sexes, not merely some skin.
6. If Adam was only male and not female, the Bible is suspect for being sexist.
7. Jesus is called the Second Adam, a human returned to perfection. Because Jesus was both male and female (at least in resurrected body), it is consistent that Adam was too.
8. In the womb, all males begin with female elements. Just like Adam. Most of those elements disappear by the second trimester. I do not interpret the Bible as magically knowing science outside its historical context, but some Christians do.
   
9. Finally, there is no evidence to the contrary except fear of new ideas.

This has several implications for transgender and intersex theology and ethics:

1. Transgender minds and intersex bodies are not in violation of God's creation of humanity as "male and female."
   
2. God has used transgenderism/intersexuality in the past for good, so God is quite capable of doing so now.
   
3. Adam is a symbol for every human being. (Remember, his name means "humanity.") This further confirms that every person has some male and some female (biologically), some masculine and some feminine (psychologically and socially).