Genesis opens with an ordered account of God making everything in six days and resting on the seventh. Christians agree that God created, that creation is good, that it is not eternal or accidental, and that humanity is made in God's image. The disagreement is about what kind of writing this is and what it therefore claims about mechanism and duration.
It is worth saying at the outset that this argument is younger than most people assume. Ancient and medieval Christian readers, including Augustine, argued about the days without any modern scientific pressure at all, and Augustine warned specifically against Christians making confident claims about the natural world that outsiders know to be false.
Genesis 1:1-2:3
1In the beginning, God created the heavens and the earth. 2The earth was formless and empty. Darkness was on the surface of the deep and God's Spirit was hovering over the surface of the waters. 3God said, "Let there be light," and there was light. 4God saw the light, and saw that it was good. God divided the light from the darkness. 5God called the light "day", and the darkness he called "night". There was evening and there was morning, the first day.
All the views below confess that God is the Creator of everything from nothing, that creation is not an accident, that humanity bears God's image and has real dignity, that sin and death entered a good world, and that Scripture is true and authoritative. They differ on genre and chronology, not on whether God made the world.
Young earth creation
The six days are ordinary days, the earth is thousands rather than billions of years old, and the flood accounts for much of the geological record.
What it claims
The Hebrew word yom with a number and with evening and morning means an ordinary day everywhere else in the Old Testament. The genealogies give a timescale. Death entering through sin implies no long ages of death before Adam. Reading the days as long ages or as literary framing is a concession made to science rather than a reading the text invites.
Who holds it
Widely held in conservative evangelical, fundamentalist, and many Baptist and Pentecostal churches, and promoted by organizations such as Answers in Genesis and the Institute for Creation Research. It is also the traditional reading of many pre-modern commentators, though not all.
The texts it stands on
Genesis 1:5 There was evening and there was morning, the first day, a formula used for ordinary days elsewhere.
Exodus 20:11 In six days Yahweh made heaven and earth, given as the ground of a literal working week.
Romans 5:12 Through one man sin entered into the world, and death through sin, which this view takes to exclude death before the fall.
Strongest case
It is the most straightforward reading of the words on the page, it holds a consistent line on the entry of death, and it refuses to let the interpretation of Scripture be quietly set by whatever the current consensus happens to be.
Hardest question
It stands against the overwhelming consensus of geology, physics, astronomy, and biology on the age of the earth and universe, which is not a small thing to set aside. Critics also note that Genesis 1 has clear literary structure, with days one to three forming realms that days four to six fill.
Holding the map
Two things are worth separating. Whether Genesis 1 intends to teach chronology is a question about the text, and Christians who agree completely about biblical authority disagree about it. Whether the earth is old is a question about the world. Confusing the two makes both arguments worse.
It is also worth knowing that this debate is far more prominent in the English-speaking world, and especially in the United States, than in most of global Christianity. That does not settle anything, but it is a useful fact to hold when the argument is presented as a test of faithfulness.
Questions that press on this one
None of these stands on its own. What you conclude here narrows what you can say there.