It is a good exercise to read Genesis 1 and try to put aside outside influences that may cause you to have a predetermined idea of what the word “day” may mean. Just let the words of the passage speak to you.
Taking Genesis 1 in this way, at face value, without doubt it says that God created the universe, the earth, the sun, moon and stars, plants and animals, and the first two people within six ordinary (approximately 24-hour) days. Being really honest, you would have to admit that you could never get the idea of millions of years from reading this passage.
The majority of Christians (including many Christian leaders) in the Western world, however, do not insist that these days of creation were ordinary-length days, and many of them accept and teach, based on outside influences, that they must have been long periods of time—even millions or billions of years.
