Why does “theory” carry starker claim absolute truth to you?

I think the word "theory" derives from the words "theo" (meaning god) and "ergy" (meaning work). So it's "god's work" literally translated.

What is meant by that is that people recognize the truth, such as truths about how the world works. The truth is called "god", or rather, "god" in the christian context is understood to be the set of all truths. So mathematical insights and physics rules are a subset of god, because they represent truths of some sort. And applying these truths in practice, i.e. building machinery according to them is the work that people put into it. So people work according to "god", i.e. according to rules. Like when you build a car, you have to know about thermodynamics. The knowledge makes you do the work. So it's insight->work, or in latin/greek: "theo-ergy" or "theory" for short.

You have to remember that all these words were invented in the 1800 so it's not unreasonable to claim that there's a heavily christian background in them since that's how people thought at the time.