God created the Earth in 6 literal days. The Bible clearly teaches this and describes each day as having an evening and a morning, just as our current 24-hour days do now:
And God called the light Day, and the darkness He called Night. And the evening and the morning were the first day.
Genesis 1:5
People today believe that science has definitively proven that the Earth is millions of years old. Many would be shocked to find out this is not the case. What is being touted by atheists, evolutionists, and most secular scientists as fact is incorrect. This false doctrine is in most science textbooks, and taught in classrooms in leading institutions around the world.
Satan’s goal is to get people to doubt the Bible and take as many people down with him as possible because he knows his time is short.
Be sober, be vigilant; because your adversary the devil, as a roaring lion, walketh about, seeking whom he may devour:
1 Peter 5:8
Scientists have used various methods over time to determine the age of the Earth. Unfortunately as technology has progressed, each of the former methods used have eventually turned out to be flawed and unreliable as new research, experiments, and data come to light. In addition, secular scientists make assumptions before even looking at the data with an open mind. Because they begin their investigation thinking that the Earth is incredibly old, and not taking into account other factors and its effects, such as a global flood, what the atmosphere was like before and after the flood, the effect of sin and the changes it caused to the planet, etc., their hypotheses includes preconceived notions, they refuse to believe and come to the truth at that point because of this.