As far as using musical instruments in the church, as far as I know there is no New Testament injunction to "...praise Him with the sound of the trumpet; praise Him with the psaltery and harp. Praise Him with the timbrel and dance: praise Him wit the stringed instruments and organs. Praise Him upon the loud cymbals; praise Him upon the high sounding cymbals..." like there is in the Old Testament.
There is, however, an exhortation to be (constantly and ongoingly) filled with the Spirit and one of the results of that is that we are to be "speaking to yourselves in psalms and hymns and spiritual songs, singing and making melody in your heart to the Lord" (
Ephesians 5:19). So, if we follow the Scriptures we are to worship God in psalms but not do it with the musical instruments that the psalms encourage us to use? It's OK to sing out "...praise Him with the sound of the trumpet; praise Him with the psaltery and harp. Praise Him with the timbrel and dance: praise Him with the stringed instruments and organs. Praise Him upon the loud cymbals; praise Him upon the high sounding cymbals..." but we shouldn't use any of those instruments we are singing about?