Where Did the Idea of “Millions of Years” Come From?

Today, the idea that the earth is billions of years old is often accepted wholesale and without challenge. But what is the origin of this widespread belief and just how convincing is it?
Theistic Evolution Is Not the Real Problem!

Even beyond the massive problems of theistic evolution, an old-earth view rejects, undermines, or minimizes Scripture’s clear teaching about when and how God created, the effects of God’s curse at the Fall, the teachings of Jesus related to the age of the creation, and the global flood.
The Significance and Expansiveness of the Flood

What does the flood teach us about God and about humanity? And was the flood global or merely local?