Why do so many disagree on the AGE OF EARTH?

This is my response to question by Lada 🏡 Prkic  Why do some people believe that Earth is between 6,000 and 10,000 years old? She mentioned science and dating methods. My answer was to long for the comment section so I put it in a buzz:

The reasons there are many disagreements in the age of the Earth is first because the dating methods are based on assumptions.

Most scientists probably don’t think about these assumptions and almost no textbooks will ever address these. What I mean is, the science is based on assumptions which are entirely untestable, almost always unspoken, rarely examined, and which must be thus taken on FAITH. Therefore it be a theory forever. 

For example, Imagine a candle burns down a quarter of an inch every hour. It's now 15 inches tall now. How long has it been burning?

In order to answer that, we have to make some assumptions. First, we have to decide how tall it was when it was first lit, since we didn't observe it before it was lit. I might believe it was 18 inches tall, while my friend believes it was 18 feet tall.

Based on that one assumption, I conclude that the candle has been burning for 12 hours while my friend concludes that it has been burning for 33 DAYS. Other factors changed the equation, such as being blown out and relit.

Since what ever experiment, formed a hypothesis, is from a Assumption and NOT an observation, the Data is also an Assumption because it can not be tested. It is not science because it can't follow through with the scientific test, and this is why the universe gets older and older in the eyes of the science community.

Yet, creationism is also based on Faith. We can trace the bloodline through the Bible from Jesus through King David, through Noah, back to Adam. Add this time length of this family linage, to (today's date - minus year of Jesus death), plus DAY SIX and you have age of Universe. FAITH also is in this community to believe that the creator made everything in six days.

The main difference between the two groups is in one group the age is and always with changed because everyone assumptions are different, and the other group the age is about the same dependable on how they solve the equation above. Both are still based on FAITH.