“Give unto the Lord the glory due to His name; Worship the Lord in the beauty of holiness” (Psalm 29:2). “All the earth shall worship You And sing praises to You; They shall sing praises to Your name” (Psalm 66:4). “All nations whom You have made shall come and worship before You, O Lord, And shall glorify Your name” (Psalm 86:9). “Oh come, let us worship and bow down; Let us kneel before the Lord our Maker” (Psalm 95:6). “Oh, worship the Lord in the beauty of holiness! Tremble before Him, all the earth” (Psalm 96:9). “Exalt the Lord our God, And worship at His holy hill; For the Lord our God is holy” (Psalm 99:9).

The only true God, who is the God of the Bible, must be worshipped. But how? What manner of worship is pleasing to Him? Is one method of worshipping God better than another? If so, what is it? How can it be discovered?

The Christian religion is a revealed religion. We can know God and His ways only as far as He is willing to make them known. Even mere human beings are known only as far as they make themselves known—how much more is this true of God! Thankfully, God has revealed Himself in the word of God. The pages of the Holy Scripture are God’s own witness to Himself. For example, we know that He is holy, because He has revealed Himself to be holy. Similarly, we know that He created the universe, that He sent Jesus Christ to be an atoning sacrifice for us, that Jesus will return to judge the world in glory, that He saves us through His grace by faith, that we should obey His laws—because He has revealed all this in His word.

In the same way, God has revealed the way His people should worship Him.

Regrettably, sinful human beings are often tempted to worship God in ways that do not please Him. They imagine new ways to worship God—ways that He has not revealed in His word. This danger can only be avoided by adhering to the worship God has revealed in His word. The Bible teaches us the regulative principle of worship. As this term suggests, our worship of God must be regulated by the word of God.

A few selected Bible passages make this clear. For example, after discussing the worship of God, Deuteronomy 12:32 says, “Whatever I command you, be careful to observe it; you shall not add to it nor take away from it.” The temptation to add or subtract from the worship of God is strong, but it must be resisted. Any substantive part of the worship of God requires a justification, or warrant, from the word of God.

Another passage teaches us the consequences of worshipping God in a way He has not commanded. “Then Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it, put incense on it, and offered profane fire before the LORD, which He had not commanded them. So fire went out from the LORD and devoured them, and they died before the LORD. And Moses said to Aaron, ‘This is what the LORD spoke, saying: ‘By those who come near Me I must be regarded as holy; And before all the people I must be glorified.’ So Aaron held his peace” (Leviticus 10:1-3). Nadab and Abihu died after they added a human invention to the worship of God.

Colossians 2:20-23 says, “Therefore, if you died with Christ from the basic principles of the world, why, as though living in the world, do you subject yourselves to regulations— ‘Do not touch, do not taste, do not handle,’ which all concern things which perish with the using—according to the commandments and doctrines of men? These things indeed have an appearance of wisdom in self-imposed religion, false humility, and neglect of the body, but are of no value against the indulgence of the flesh.” The Bible condemns all “self-imposed religion” or “will-worship” (King James Version) as commandments and doctrines of men.

Jesus rebuked the woman at the well, because she and her fellow Samaritans “worship what you do not know.” “But the hour is coming, and now is, when the true worshipers will worship the Father in spirit and truth; for the Father is seeking such to worship Him. God is Spirit, and those who worship Him must worship in spirit and truth” (John 4:24-25).

The Westminster Confession of Faith summarizes the regulative principle of worship. “But the acceptable way of worshipping the true God is instituted by Himself, and so limited by His own revealed will, that He may not be worshipped according to the imaginations and devices of men, or the suggestions of Satan, under any visible representation, or any other way not prescribed in the holy Scripture.” The Westminster Larger Catechism 108 says, “The duties required in the second commandment are, the receiving, observing, and keeping pure and entire, all such religious worship and ordinances as God hath instituted in his Word; particularly prayer and thanksgiving in the name of Christ; the reading, preaching, and hearing of the Word; the administration and receiving of the sacraments….”

The Westminster Larger Catechism 109 says, “The sins forbidden in the second commandment are, all devising, counselling, commanding, using, and anywise approving, any religious worship not instituted by God himself…corrupting the worship of God, adding to it, or taking from it…”

The regulative principle of worship is important for another reason. We are taught that “whatever is not from faith is sin” (Romans 14:23). All of our worship must be from faith; otherwise, it is sin. So we must have faith that God will accept what we do in worship. But how can we have this faith? “So then faith comes by hearing, and hearing by the word of God” (Romans 10:17). Our faith that God receives our worship rests on the foundation of the word of God. Any worship not based in the Holy Scripture is not of faith; therefore, it is sinful.

What has all this to do with the communion cup? Very much! The sacrament of the Lord’s Supper is part—indeed, a central part—of the worship of God. All Christians are commanded to receive, observe, and keep it “as God hath instituted [it] in His word.” It would be a sin to corrupt it, add to it, or take from it. No matter what reason or reasons Christians may have for changing the Lord’s Supper, such changes stand condemned by God’s word. Christ is the only king of the Church, her only lawgiver, and faithfulness to Him requires biblical worship.

So we must ask: How did God institute the Lord’s Supper? Did Christ use wine? Did He use grape juice? Is it even possible for us to know what He used as the contents of the communion cup? Only a study of the word of God can answer such questions.