Here are the Theories proven as truth.
Copernican Theory. This theory was discovered by Copernicus in 1543. This Copernican Theory or Heliocentric Theory was supported by Galileo after his discovery of a little astronomy saying it is true that the galaxy revolves around the sun. When he supported this one, everybody opposed him because people believed the Geocentric theory, the sun revolves around the galaxy. In fact this is proven also in the Bible. However, as science develops, Copernican Theory was proven to true so this is a science now.
In 17th century, a theory was released that inside of the earth is fire that is being heated up. However, in 19th century, people laughed about this theory because no one believed that there is a fire inside the earth. However, Geophysicist Beno Gutenberg discovered the outer core in 1914 and Geophysicist Inge Lehmann in 1936, discovered the inner core. The Bible also explained 3, 500 years ago that inside of the earth is s fiery element. Thus this theory is proven to be true and it is science.
A theory says that water goes up and and then goes down. This is why no matter how long it rains, the earth is not filled up with many water. This theory remained to be a theory until Perrault and Marriotte discovered the cycle of water in the 17th century. Thus this theory is proven to be true and it is a scientific knowledge in this age.
These kinds of theories are very much appreciated because we had discoveries about geology and astronomy.