Morality is always derivative. It stems from one's worldview.

Because a human is a someone and not a something, the source of human life must also be a Someone - not the blind, automatic forces of nature, as philosophies like naturalism and materialism tell us.

A worldview is not the same things a formal philosophy, otherwise it would only be for philosophers. Even ordinary people have a set of convictions about how reality functions and how they should live. Some convictions are conscious while others are unconscious but together they form a consistent picture of reality.

An idol is not necessarily something concrete, like a golden calf. It can also be something abstract, like matter. Is matter part of the created order? Sure it is. So the philosophy of materialism qualifies as an idol in the biblical sense.