When we baptize our children into the Catholic Church, we promise to raise them in the Catholic faith. The Code of Canon Law states:
Can. 868 §1. For an infant to be baptized licitly: 1/ the parents or at least one of them or the person who legitimately takes their place must consent; 2/ there must be a founded hope that the infant will be brought up in the Catholic religion; if such hope is altogether lacking, the baptism is to be delayed according to the prescripts of particular law after the parents have been advised about the reason.
So, in conferring baptism, the Church likewise hopes that the baptized will be brought up Catholic and one of the requirements in requesting baptism is in a promise to raise the child Catholic. Pretty simple and understandable.
Now, one of the essential parts of living the Catholic faith is attending Sunday Mass. The Catechism States:
2177 The Sunday celebration of the Lord's Day and his Eucharist is at the heart of the Church's life. "Sunday is the day on which the paschal mystery is celebrated in light of the apostolic tradition and is to be observed as the foremost holy day of obligation in the universal Church."
In fact, it is so important, it is mandatory.
2180 The precept of the Church specifies the law of the Lord more precisely: "On Sundays and other holy days of obligation the faithful are bound to participate in the Mass. The precept of participating in the Mass is satisfied by assistance at a Mass which is celebrated anywhere in a Catholic rite either on the holy day or on the evening of the preceding day."
So being part of the Catholic Church includes the obligation of participating in the Mass. Being baptized, even the youngest child is included in the faithful and hence is bound to participate in the Mass.
Now, I understand very well that young children have difficulty sitting still, don't understand the Mass, and are prone to be a distraction. Mine are no different. But does that excuse them from not attending Mass? I don't see how it would. The Church does not say that only those who understand the Mass should attend. How would we come to understand it if we didn't attend? Through books or videos? The Mass is more than paper and film. God is at the Mass. Since when can experiencing God be captured in any way but through living it?
Just because an infant or young child has trouble being quiet and sitting still does not mean they are not getting anything out of being there. They are "a testimony of belonging and of being faithful to Christ and his Church. ... They testify to God's holiness and their hope of salvation." (CCC 2182)
There is grace abundant at the Mass even by just being there to hear God's Word and recognizing Him as special, as God. Cecilia is not even 3 yet and she is already trying to recite the Nicene Creed when we do, she loves putting the collection in the basket, she tries to sing with us, she recognizes Jesus when the crucifix proceeds up the aisle and recently, when we receive the Eucharust, she has been asking to receive him too: "Want some." Does she understand she is asking to receive God? Probably not. But she wouldn't be doing most if any of this if she had not been experiencing the Mass for almost 3 years now. Children learn as they grow. They learn through repetition and experience. It is doing a great disservice to children to leave them in a nursery for 4 years before bringing them to live the Mass.
Can children be a distraction? Sure. Sometimes no matter what we do, they will be difficult. But that does not excuse not bringing them. The woman in front of me with a short shirt revealing her tatoo is a distraction. The teen wearing frayed jean shorts and flipflops is a distraction. The latecomers opening and closing doors and asking me to move are a distraction. The ones who get up to go to the bathroom are a distraction. The person with a cold who sneezes and coughs can be a distraction. The man who reads the bulliten during the homily is a distraction. The woman who rustles through her purse to get her checkbook and pen is a distraction. All of us can be distractions. Should we all not come too? Would you offer or recommend separate accommodations for each of these people so others aren't distracted? Or should we all be together as a community of faith and accept the limitations of each other in charity and offer up these annoyances in union with Christ?
Babies. Toddlers. Children. They are a most precious part of the Body of Christ. Skip the nursey. Bring them to Church!