What is the meaning of "This world is a realm of norms; it is not permissible to abandon it while having the ability to engage with it, and preoccupation with it is polytheism, while abandoning it is a sin, and not acknowledging its importance is heresy"?

In summary: The meaning of the world being a realm of immutable laws is that Allah created it with consistent patterns and connected causes to their effects. These are permanent and fixed laws that apply to everyone. Neglecting to utilize these means, when one is able to, varies in its ruling. However, giving them complete reliance is shirk, contradicting tawakkul (reliance on Allah). Denying that they are causes is a defect in the Shari'a and a deficiency in intellect.

Shaykh al-Islam Ibn Taymiyyah reported from the scholars their saying: "Turning to causes [with complete reliance] is shirk in tawhid, denying causes to be causes is a deficiency in intellect, and completely disregarding causes is a defect in the Shari'a."