Science is the practice of finding good Explanations.
Science is a way of dealing with theories regardless of whether or not one believes them. They are judged according to whether or not they’re good explanations. And if a particular explanation ends up being the only explanation that survives the intense criticism that reason and science can apply, then it’s not so much adopted at that point as just not discarded. It has survived for the moment.
There is a common misconception that science reduces to what is testable. Although much of science consists of testable theories, testability is not a requirement. Rather we should look at if a theory is a Good Explanation.
The is also another common misconception that there exists a bright line between science and every other discipline where we purport to describe reality (e.g. philosophy). But ultimately they're all disciplines looking to find Good Explanations.