Joel Beeke and Paul Smalley on God's Spirituality and the Simplicity of Worship

Beeke and Smalley write,

Worship of the Holy One is acceptable only if it conforms to the requirements of his Word. God made the old covenant ceremonies obsolete by the finished work of Christ (Heb. 8:13; 9:1-14). We have no need of temples, priests, and altars, for Christ is all to us (13:9-16). The complex system of old covenant worship has been replaced with the simplicity of worship in spirit and truth, in which we read the Word, pray the word, sing the Word, preach the Word, and see the word made visible in baptism and the Lord's Supper.

When people add sacred objects and actions ("human inventions") to God's ordained worship, they implicitly rebel against his spirituality and seek a sensual, material religion. Men naturally seek fleshly worship that pleases them instead of spiritual worship that is befitting God's nature. This is one of the great errors of Roman Catholicism. Its multiplication of holy days, ceremonies, and worldly pomp of the clergy, along with its elevation of ascetic mistreatment of the body, outdoes anything commanded under the Old Testament--and without divine sanction in the new covenant. Such practices distract worshipers from Jesus Christ, the only Mediator. They also open the door for large numbers of people to outwardly worship God without a heart to glorify him--or, as was said of the Samaritans, to "fear the LORD" and yet serve "their graven images" (2 Kings 17:33, 41).

Beeke, Joel and Paul Smalley. Reformed Systematic Theology. vol. 1. Revelation and God. Wheaton, IL: Crossway. 2019, pg. 620-1. emphasis mine