Nothing wrong with no musical instruments. But, some of the other stuff there is odd...
I do like A Cappella. I had visited this particular church a few times. They take great pride in that they worship with no musical instrument. The first several songs half of the church was not singing but just sitting in the pews. However, there was one song that obviously everyone like and it sounded so beautiful. Of course, we are not singing for each other. We are to praise the Lord. Its a heart thing. Is it the musical instruments or is it our attitude?
Nothing wrong with no musical instruments.
They believe that using musical instruments (organ, piano, etc.) in the worship service sinful.