The early Church Fathers and Medieval theologians did not know about radiometric dating or how rock layers formed, so a few thousand years was a reasonable guess for the age of the universe.
In 1650, the Anglican archbishop James Ussher calculated that the world was created around 4004 BC based on the genealogies recorded in the book of Genesis.
For the first 1700 years of Christian history, belief in a literal six-day creation and a world that was a few thousand years old was widespread within Christendom.
This is because, until the early Modern Period, there was no reason to think otherwise.
A few assign a much older age to the universe than to Earth.
Although most mainstream scientists and most of the developed world now accept the theory of evolution and the scientifically established age of Earth and the universe, there is still a group of people that resist the status quo and insist, based on a particular literal interpretation of Genesis 1-11 in the Hebrew Bible, that the universe is only 6,000 years old and was created in six literal days.
As of 2014, 42% of Americans believe that the universe was created about 10,000 years ago and that all life was created more or less in its present form at that time.
A 2017 Gallup creationism survey found that 38% of adults in the United States inclined to the view that "God created humans in their present form at one time within the last 10,000 years" when asked for their views on the origin and development of human beings, which Gallup noted was the lowest level in 35 years.
The first major comprehensive draft of Genesis was composed by the Yahwist in the late 7th or the 6th century BC, during the Babylonian captivity, with later additions made by the priestly source in the post-exilic period.