Those who would worship God must worship in spirit and in truth.

Jesus said that we must worship God in spirit and in truth.

John 4:23-24 But the hour cometh, and now is, when the true worshipers shall worship the Father in spirit and in truth: for the Father seeketh such to worship him. God is a Spirit: and they that worship him must worship him in spirit and in truth.

As John explains, this is not optional simply because God is spirit and must be worshiped in spirit.