The Principle of:

EXALTATION - Will it glorify God? (I Cor. 10:31)

EMULATION - Will it be consistent with Christlikeness?  (I John 1:5-7; 2:5-6)

ENCROACHMENT - Will it infringe upon the Lordship of Christ in the life of believers? (Romans 14:1-8)

EXPEDIENCE - Will it be spiritually profitable? (I Cor. 6:12)

EDIFICATION - Will it edify in the faith? (I Cor. 10:23)

EXCESS - Will it hinder growth or service? (Hebrews 12:1)

ENSLAVEMENT - Will it tend to enslave? (I Cor. 6:12)

EQUIVOCATION - Will it encourage hypocritical covering of sin? (I Peter 2:16)

EXAMPLE - Will it possibly cause a weaker brother/sister in Christ to stumble? (I Cor. 8:9, 13)

EVANGELISM - Will it detract others from coming to Christ? (I Cor. 10:27-29; 14:23-25)

"And do not get drunk with wine, for that is dissipation, but be filled with the Spirit, speaking to one another in psalms and hymns and spiritual songs, singing and making melody with your heart to the Lord; always giving thanks for all things in the name of our Lord Jesus Christ to God, even the Father; and be subject to one another in the fear of Christ." (Ephesians 5:18-21 NASV)

From the above passage the following observations can be made:

1. Principle of the new song.  The natural outflow of the spirit-filled life is singing (19), giving thanks (20), and submission (21).  The singing in this passage is consistent with the principle of the new song.  The new song is always associated with redemption (Psalm 33:1-3; 40:2, 3; 96:1,2; 98:1,2; 144:9; 149:1; Rev. 5:9).  The new song is offered with praise and thanksgiving by the redeemed heart as a result of the joy which only Christ can give.  Verse 19 explains that singing to God is to be offered with or from the heart.  The redeemed and spirit-filled heart is the essence of the new song.  God is not honored and does not accept a song from one whose heart is not right with Him (Amos 5:21-24).
    

2. Purpose of the new song.  Paul explains that singing is to be to the Lord.  Singing with a spirit-filled heart to the Lord is an expression of worship, a sacrifice of praise.  The purpose of the new song is to exalt our great God and Savior.
    

3. Personality of the new song.  Paul instructs us to speak to each other with psalms, hymns, and spiritual songs with singing and melody.  God is honored and Christ exalted when three general types of songs are sung from the heart of a spirit-filled person:

1. Psalms sung by the early church were primarily Old Testament Psalms.  They emphasized the nature and works of God.  Some of the songs we sing today which speak of God, such as "A Mighty Fortress is Our God" can be considered a modern psalm.
    

2. Hymns were songs of praise which focused upon the work of our Lord Jesus Christ.  An example of a hymn is "The Old Rugged Cross".
    

3. Spiritual songs were probably songs of personal testimony which expressed the truths of grace and salvation in Christ.  Examples of spiritual songs include, "O, How He Loves You and Me" and "I'd Rather Have Jesus Than Anything".

Additional principles can be found in God's Word which can be used to help us determine what type of music will honor God and be profitable for the Christian.  Some of these are listed from the works of Dr. Ernest Pickering and Dr. John
MacArthur -

1. Its message is Scriptural (Col. 3:16).  It must present a message that is true to the Word of God and be doctrinally sound.
    

2. It should lead the musicians and hearers to think in biblical patterns and avoid being suggestive of evil either in message or in musical arrangement (Philippians 4:8).
    

3. It should help us to honor God with our bodies (I Cor. 6:19-20).
    

4. It will maintain a balance between "Spirit" and "understanding" (I Cor. 14:15).
    

5. It will contain words that are full of beauty, dignity, reverence and simplicity, words that are worthy of the worship of our Holy God.
    

6. It will be free of mental association with worldly musical styles and evidence a Holy and consecrated character (Romans 12:2; I John 2:15).
    

7. It should be expressive of the peace that accompanies the Christian life, not the clamor, confusion, din and turmoil of the world (Col. 3:15-16).
    

8. It should be characterized by musical preciseness, finesse of poetic technique, and should evidence a structure of harmony and order (I Cor. 14:40).
    

9. It should promote and accompany a lifestyle of godliness, modesty, and holy quietness (I Peter 1:16; Titus 2:11-12).
    

10. It should not contribute to the temptation of new or weak believers (Romans 14:13, 21; 15:2).