This is now the best book out there on why children should be present and participating in the worship of Christ's church. I will recommend it before Parenting in the Pew.
Helopoulos rightly prioritizes worship of God, love for God, delight in God, and communion with God (individually and corporately) as the goal of the Christian life, and he rightly prizes the ordinary means of grace (the Word, the sacraments, and prayer) in the corporate worship of God's people as the greatest instruments whereby the Spirit of God will form the hearts of children to maturity in Christ. To remove children from worship, for whatever reason, steals blessing from them and injurs or weakens the body.
In the last three chapters, he addresses dubious parents (to whom he gives helpful concrete advice on how to prepare for Sunday and how to help your child thrive in worship), church leaders (whom he reminds that the culture of the church probably will communicate hospitality to children only if they themselves communicate hospitality to children), and various alternative programs (Sunday school, children's church, worship training) and objections. He argues his case persuasively and powerfully.
The only place where he didn't quite do his best was in arguing against children's church as a replacement for children-in-worship. He assumes that children's church will seek essentially to entertain children, which he rightly notes is not actually good preparation for worship, which is not about us but about the triune God of our confession. He does not, however, address children's church models that are genuinely worshipful (e.g., the model of the Hearts Alive curriculum). I do think that even that sort of children's church is inferior to children-in-worship, but Helopoulos would've done well to address a well-done children's church model rather than just the easy straw man.
That said, I wish literally everyone who loves the Church would read this book. The author is a pastor who has children, loves children, and wants to see children learn the joy of worship; he makes his case theologically and skillfully; he avoids entirely the charge of naiveté; and he clearly loves the church, which is a large part of what makes his case so persuasive.
Anyway, read this book. It'll take you an hour or two. And then give it to your pastor or your staff and have them read it, too.