Other forms: reductionists
If someone believes that you can break complex theories into simple, smaller parts, you can call that person a reductionist. A reductionist might explain religion, for example, as simply an attempt to explain why the world exists.
When you describe someone as a reductionist, you are explaining that person's philosophical stance on something — it might be science, human behavior, history, or religion. The preference for simplifying, especially when it involves breaking complicated ideas into smaller, less complicated ideas, is reductionist. This philosophical idea has been around since the 1940s, and the word itself stems from the Latin reducere, "bring back."