It always amazes me when I hear people say that music does not matter. Or that music is not black and white. Once you understand the purpose of music and what music does to our body, emotions and spirit you start to see that music is very black and white.
This is a short article written by Pastor Corey Seulean.
My thoughts on music as we sing to God in church and in private.
1 Thessalonians 4:4-7 KJV
 That every one of you should know how to possess his vessel in sanctification and honour;  Not in the lust of concupiscence, even as the Gentiles which know not God:  That no man go beyond and defraud his brother in any matter: because that the Lord is the avenger of all such, as we also have forewarned you and testified.  For God hath not called us unto uncleanness, but unto holiness.
Ephesians 4:22-24 KJV
 That ye put off concerning the former conversation the old man, which is corrupt according to the deceitful lusts;  And be renewed in the spirit of your mind;  And that ye put on the new man, which after God is created in righteousness and true holiness.
Psalm 96:9 KJV
 O worship the Lord in the beauty of holiness: fear before him, all the earth.
Holiness is important to worship God in a way that He wants to be worshipped.
2 Corinthians 6:17-18 KJV
 Wherefore come out from among them, and be ye separate, saith the Lord, and touch not the unclean thing ; and I will receive you,  And will be a Father unto you, and ye shall be my sons and daughters, saith the Lord Almighty.
Separation from what God calls unclean is important. Christians should recognize the worlds music at the very least as being unclean.
Psalm 40:2-3 KJV
 He brought me up also out of an horrible pit, out of the miry clay, and set my feet upon a rock, and established my goings.  And he hath put a new song in my mouth, even praise unto our God: many shall see it , and fear, and shall trust in the Lord .
Our new songs should be different from the horrible pit from which God saved us.
New does not equal bad. The same as the world from which God saved us does equal bad.
1 Corinthians 6:9-11 KJV
 Know ye not that the unrighteous shall not inherit the kingdom of God? Be not deceived: neither fornicators, nor idolaters, nor adulterers, nor effeminate, nor abusers of themselves with mankind,  Nor thieves, nor covetous, nor drunkards, nor revilers, nor extortioners, shall inherit the kingdom of God.  And such were some of you: but ye are washed, but ye are sanctified, but ye are justified in the name of the Lord Jesus, and by the Spirit of our God.
God expects us to be different from the world from which we were saved.
1 Peter 2:9-11 KJV
 But ye are a chosen generation, a royal priesthood, an holy nation, a peculiar people; that ye should shew forth the praises of him who hath called you out of darkness into his marvellous light:  Which in time past were not a people, but are now the people of God: which had not obtained mercy, but now have obtained mercy.  Dearly beloved, I beseech you as strangers and pilgrims, abstain from fleshly lusts, which war against the soul;
We should abstain from fleshy lusts. Surely we can recognize the fleshy lusts associated with the music of the world!
Ephesians 5:18-19 KJV
 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;
Hymns are mentioned in Scripture. It’s undeniable. What makes hymns acceptable was not the “oldness” but rather their holiness and truth.
In summary, newness is not equal to wrong. We are called to be separated from the world in music as well. All instruments can have their proper place in worship to God. When it is all said and done, our worship of God should first and foremost be to please God not ourselves. And yes, there is liberty in worshipping God in different ways as long as biblical principles are not violated.
Revelation 4:11 KJV
 Thou art worthy, O Lord, to receive glory and honour and power: for thou hast created all things, and for thy pleasure they are and were created.