"Churches, above all the Catholic Church (because of its great antiquity and resources), have spent much effort developing doctrines. According to Catholic doctrine, for example, it is not sufficient to believe Christ existed. You must believe that he was the son of God, that he was crucified, that he arose from the dead, and that he ascended to heaven. You must believe that his birth was a virgin birth, and that Mary's birth was also a virgin birth. You must believe in transubstantiation. I could go on and on."

And I believe in all of this (except transubstantiation since I'm not Catholic). To be a Christian you should believe what is stated in the Nicene Creed:

We believe in one God, the Father, the Almighty, maker of heaven and earth, of all that is, seen and unseen. We believe in one Lord, Jesus Christ, the only Son of God, eternally begotten of the Father, God from God, Light from Light, true God from true God, begotten, not made, of one Being with the Father. Through him all things were made. For us and for our salvation he came down from heaven: by the power of the Holy Spirit he became incarnate from the Virgin Mary, and was made man. For our sake he was crucified under Pontius Pilate; he suffered death and was buried. On the third day he rose again in accordance with the Scriptures; he ascended into heaven and is seated at the right hand of the Father. He will come again in glory to judge the living and the dead, and his kingdom will have no end. We believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son. With the Father and the Son he is worshiped and glorified. He has spoken through the Prophets. We believe in one holy catholic and apostolic Church. We acknowledge one baptism for the forgiveness of sins. We look for the resurrection of the dead, and the life of the world to come.

I chose the Nicene Creed because it sums it up nicely. If you believe in this then it doesn't matter if the world was literally created in 6 days or not. Believing that God created the heavens and the earth, that Jesus is the son of God and our Lord, that he died on the cross for our salvation, and belief in the guidance of the Holy Spirit is what is required for salvation and to be a Christian.

"Consigning much of the bible to poetry or metaphor is not taking it seriously."

For one thing, I don't consign "much" of the Bible to poetry or metaphor. But parts of the Bible are definitely poetry and metaphor, such as Psalms, Job, Song of Solomon, etc. The Bible isn't meant to be one big history book, but is instead full of different types of literature that all point to God. I believe however that all of the books of the Bible are important and inspired by God, and are spiritually true even if not literally true. The events of Job may not have literally occured, but the spiritual meaning of the story is very important, far more important than anything in a Dickens novel. I'll quote C.S. Lewis here on inspiration and the Bible:

"not all scripture is inspired for the same purpose or in the same way...inspiration is a single thing in the sense that, if present at all it is always present in the same mode and the same degree; therefore, I think, rules out the view that any one passage taken in isolation can be assumed to be inerrant in exactly the same sense as any other"

The majority of the NT is meant to be taken literally, since it concerns our salvation and our faith. If you believe that Christ is just a metaphor then what's the use of your faith? It's important for our faith to view the NT literally, because that is what our faith stands upon. However it's not important to take the Book of Job literally since it has no bearing on our faith. It is important however to take the message of the book of Job literally, since it tells us important spiritual truths. The importance of Job is the meaning behind the story, not the literal reality of the story itself.