"Worldliness is defined in 1st John 2:15 as appealing to the lust of the eyes, the lust of the flesh, and the pride of life. To understand what appeals to our lusts, read Galatians 5:16-20. Most pre-rock-n-roll popular music in America grew out of forms originating among God's people. Many of the popular songs of the early '50s were Gospel songs. By contrast, rock and roll originated with the children of disobedience. It is worldly by design.
"Mature Christians who exercised themselves in the use of Scripture so as to sharpen their senses to discern good and evil (Hebrews 5:14) recognized it immediately as the music of rebellion. Of course, they were ridiculed and scorned and ignored, but it was only a few generations later that millions of our children were led into the occult by their rock-n-roll heroes.
"Another important point to take from the necessity that we worship God in spirit is that genuine worship is never without the mind fully engaged, fully aware. Any form of worship that encourages one to suspend active engagement of their rational mind during worship is not the sort of worship that God wants. You cannot truly worship in spirit without the understanding being engaged (1st Corinthians 14:15)."
Pastor Jerry Scheidbach, Lighthouse Baptist Church of Santa Maria, California, in his book "The New Cart Church: Doing the Right Thing the Wrong Way"