The LORD spoke to Moses, saying, “Take Aaron and his sons with him, and the garments and the anointing oil and the bull of the sin offering and the two rams and the basket of unleavened bread." (Leviticus 8)
Certain very physical acts had important religious (Spiritual) significance. Because of some oil, blood, fabric, burned flesh and such the proper worship of God was instituted. Ritual is important because, among other things, it does something. It effects some sort of change in the real world.
An unpolished thought