I remember something that happened at a gospel meeting I attended almost twenty years ago. As I was sitting, listening to the sermon, I noticed that a man in the pew in front of me was reading a paperback book. He read throughout the preaching and even through the singing. At one point he put that book down and picked up another one and started reading it. I don't know why he was there, but he had not come prepared to worship God.
God requires us to worship Him in spirit and in truth. "God is Spirit, and those who worship Him must worship in spirit and truth" (John 4:24). What God wants most from us during our times of worship is our heart, our mind - our attention. Just because we are sitting among people who are worshiping in spirit and truth does not mean we are worshiping. No one is "guilty" of worship by association. While worship may be something we do collectively, it is still very much an individual activity. By that I mean it is a time in which we need to "connect" with God in a spiritual manner as individuals.
There are times when Christians involve themselves in things at worship services that show a lack of interest and involvement in what is taking place. Worship is not a time to check out social media on our cell phones or tablets, send or reply to texts, make out our grocery list, give ourselves a manicure, balance our check book, catch a few z's, or even read a paperback novel. It is a time to pray, remember the Lord's death, give, sing and study God's word. It is a time for our spirit to be engaged in praise and admiration of God.
We have all week to get non-spiritual matters taken care of. We only meet a few hours a week to worship God and study His word. Can God have our attention during this time? Is that asking too much?