A singular, pure, practical allegiance allows the worship to be acceptable; because it will allow the worship to be done from the heart, soul and mind – to be done with the understanding.
The apostle Paul points to this important principle of understanding what you are doing, and meaning it in his first epistle to the Corinthians:
What is it then? I will pray with the spirit, and I will pray with the understanding also: I will sing with the spirit, and I will sing with the understanding also. (1 Corinthians 14:15 KJV)
The Corinthians had problems in properly using the spiritual gifts that had been given by the Holy Spirit. They were utilizing what they perceived to be those spiritual gifts without others being able to understand what they said, or even being able to understand themselves. Paul thus instructs them that it was proper and good to use the gifts of the Spirit, but that it should be done with the understanding.
Brother Paul had already shown the indispensability of worshipping with the understanding to the Corinthians in speaking of their corruption of the Lord’s Supper:
Wherefore whosoever shall eat this bread, and drink this cup of the Lord, unworthily, shall be guilty of the body and blood of the Lord. But let a man examine himself, and so let him eat of that bread, and drink of that cup. For he that eateth and drinketh unworthily, eateth and drinketh damnation to himself, not discerning the Lord's body. For this cause many are weak and sickly among you, and many sleep. (1 Corinthians 11:27-30 KJV)
Damnation was the result of partaking of the emblems in the supper without the proper understanding of their meaning, if it be done “unworthily.” The proper spirit, attitude and understanding of that which was done was not optional, it was a moral necessity.
When addressing himself to the churches of Ephesus and Colossae, the apostle emphasizes the need for understanding in singing.
And be not drunk with wine, wherein is excess; but be filled with the Spirit; Speaking to yourselves in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord; Giving thanks always for all things unto God and the Father in the name of our Lord Jesus Christ; Submitting yourselves one to another in the fear of God. (Ephesians 5:18-21 KJV)
And,
Let the word of Christ dwell in you richly in all wisdom; teaching and admonishing one another in psalms and hymns and spiritual songs, singing with grace in your hearts to the Lord. (Colossians 3:16 KJV)
It is to be done with the understanding, from the heart, full of meaning. This is the very point Jesus was making when He taught His disciples: But when ye pray, use not vain repetitions, as the heathen do: for they think that they shall be heard for their much speaking. (Matthew 6:7 KJV)
Vain repetitions are those void of meaning, those said without understanding what it means just because it sounded good.
Without a proper understanding of what is being done, and doing it for that reason, worship is meaningless. It cannot be worship in its true sense for there is no attitude of the heart, mind and soul expressed in action toward God, because it is not known whether the action engaged in expresses the proper attitude of the heart, mind and soul or not, or even if the action is directed toward God or some other! Without understanding there can be no expression of the emotions or will. The actions become senseless and reasonless. Surely, God cannot be expected to be pleased with such worship.
Conclusion
To worship “in spirit” one must have:
1) A singular allegiance – “Thou shalt worship the Lord thy God, and him only shalt thou serve” (Matthew 4:10; Deuteronomy 6:13; 10:20).
2) A pure allegiance – “Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy strength, and with all thy mind” (Luke 10: 27; Deuteronomy 6:5; 10:12).
3) A practical allegiance – “And why call ye me, Lord, Lord, and do not the things which I say?” (Luke 6:46; Malachi 1:6).
4) Understanding – “Ye worship ye know not what: we know what we worship” (John 4:22).
Each of these four components need to comprise our worship for it to be truly “in spirit” and pleasing to the Father.