Somebody (internet name = Josh) tried to explain why evolution is true and it was very well done. I'm putting it here.

Is evolution "only a theory" or do you take it seriously?

Gravity is only a theory. I don't see many people eager to test it by taking a long walk off a short pier.. germ theory is another theory that's mostly taken seriously in the 21st century. We went from believing plagues and other illness were due to the wrath of God, demonic possession, and witchcraft, to being able to treat disease at its true source; microorganisms. The theory of evolution is greatly responsible for advancements in modern medicine since germs evolve immunities to antibiotics over the period of a few generations.. genetic mutations happen all the time. If a bunch of minor genetic mutations happen, isn't it rational to believe that enough small mutations will eventually become major ones and you'll see a major change within a species? I just don't think deniers comprehend the true timescale these things take to happen. Millions of years.. if you believe the Earth is 6,000 years old, scroll on through to the next question; you can't be saved from your idiotic ideology.