God is very picky about how He is worshipped

…do not inquire after their gods, saying, 'How did these nations serve their gods? I also will do likewise.'  You shall not worship the LORD your God in that way; for every abomination to the LORD which He hates they have done… Deuteronomy 12:30-31 

God not only condemns the false worship of false gods, He utterly rejects those who claim to worship Him in the ways in which people worship their false gods.  This tells us two important truths:

First, true and false worship exist.  The idea that it doesn’t matter who, or what, or how one worships as long as one is sincere, is altogether false.  The only true worship is worship of the only true and living God according to the ways He has required in His Word.

Second, any and all worship of any other god besides the one and only true and living God is utterly false and is rejected by God.

Third, the God of the Bible is not only the only God who may be worshiped, we must never worship the true and living God according to the methods the world employs in the worship of their false gods.  God not only hates what they do, He hates it when so-called Christians do these things claiming that they are worshiping Him.

Consider how many entertainment-based, carnival-like, pep-rallies in our day in many so-called churches are presented and thought of as worship.  True NT worship must be firmly grounded in reverently singing praises, praying, hearing His Word preached, and in the administration of the sacraments of Baptism and the Lord’s Supper.  When anyone adds to, or subtracts from these, or does these without reverential fear of God, the result is not worship.  And it will be rejected by God.