The Bible begins with the statement, 'in the beginning God created the heavens and the earth'. Now this to me is axiomatic and worthy of dying for. That is, Christianity is based on the notion that a brilliantly intelligent cosmic being is behind the created order, it is the product of his creative brilliance.
Beyond this Christians disagree, and with a great degree of strong feeling. There are those who are absolutely convinced that the Genesis account must be interpreted literally and that God created the order in exactly six 24 hour days in exactly the manner described in Gen 1-2. Other Christians are not so sure and are happy to accept some of the notions of science including an older earth. They reject that there is a need for six literal 24 hour days noting that the Hebrew for "day" is used differently through the OT, that the sun and moon were created on the fourth day, and that there is clear symbolism in the text. They thus accept the general outline of Gen 1-2 in terms of order, reject any notion of evolution, but argue for creation over a longer period. Another term which falls into this category is "Intelligent Design" which refers to those across a number of the religious persuasions whether Christian or not who believe there is a great designer, reject evolution, but do not accept the literal perspective of young earth creation. Others are comfortable harmonising 'God created' with evolution, arguing for theistic evolution i.e. God caused the development of the living world through a process like evolution but not purely natural selection.
Now I have my own view on this which aligns more with the second position above, but I would not die for the detail. I don't know enough about evolution, about the intention of Genesis, about the complex arguments involved. I am totally unimpressed with macro-evolution and do not want to compromise toward what is not proved, evolution being a scientific philosophy rather than emperical science any more than literal 6 day creation is. So for me, if I was asked 'do I believe God created the world over a long period of time but in principle according to the order of Genesis 1-2 I would answer, probably. However, I would not die for it. I would not split a church for it. I would perhaps argue for my position, but I would not get all passionate and flip my lid over it.
However, I would get hot under the collar for the notion 'God created the heavens and the earth'. Now this is a premise the Biblical account is built on. The universe is not a product of chance or a deistic uninvolved God, it is the product of a creative, loving being who created this glorious univers and probably others ones, and placed us on this planet as the apex of his creation as his beloved children to live in eternal relation with him. We screwed it up, but he still loves us and is determined to save us while preserving our ability to say no if we so desire. The 'how' of creation is beyond me and not necessary to an authentic Christian faith.
I am dismayed at the fundamentalism of many Christians over all this stuff. It is dumb as it divides us, means we give a confused voice to the world, and often employs dodgy science, exegesis and theology from people at both the more literal and evolutionary end of the argument. Let's stick to the big picture that the Scriptures affirm and we can agree on, and by all means discuss the issue, argue for our view and challenge one another's thinking. But let's not obscure the essential: 'God created the heavens and earth!'