My last school was a boys' school and we were never allowed to say anything they did was wrong, only that it was inappropriate. So overtly sexualised posturing, sexist language and racist language were never "wrong", just "inappropriate". I don't like this approach, but I will adopt it for the forthcoming argument.
Matthew 18: 1-6 is often cited as a good reason for us to suffer children at Mass irrespective of their behaviour. I quote it at the end of this piece, in case your memory needs refreshing.
The child that Jesus calls and puts in the midst of the disciples is not described. However verse 2 does not end with the words, and after the child had thrown its toy camel at a disciple, hollered loudly for its mother and tugged at Jesus's beard and hair... . An inappropriately behaved child would not make any sense in this Gospel passage. The child was meek, the child was called by Jesus and the child responded appropriately. Being placed in the midst of the disciples makes the child a teacher and a most profound one at that. As the Son is infront of the Father, so the child is infront of Our Lord, and so ought we be too. Never, never get in the way of a child and its faith, the consequences are terrifying.
It is the child who simply doesn't appreciate that church is a sacred space, different from the living room, that can lead to inappropriate behaviour, both from the child and its parents. It can never be appropriate to feed a child (save breastfeeding) at Mass,. How will a child ever appreciate the Eucharist if it is leaving great lumps of Jaffa cake smeared over the pews? It is never appropriate to bribe a child to be quiet during Mass. It is never appropriate to hold a conversation with a child that has no relevance to the Mass whilst the Mass is taking place. Is it appropriate that there is a child whose parents let it run all over the sanctuary before Mass pulling the flower arrangements to bits? Are not all these types of behaviour likely to get in between the child and its growing faith.
If we look at Luke 2:41-43, it seems clear that children were only expected to journey to the Temple in Jerusalem on reaching the age of 12. An age where appreciation of and appropriate behaviour during religious ceremonies would be expected. I'm not saying 12 is the best age, indeed I'm not suggesting any age requirements only an understanding that perhaps the child needs some appreciation of what is happening.
The things that would be considered inappropriate in the public gallery of a law court, or at a funeral, or at a gallery of priceless artifacts aren't somehow appropriate at Mass.
The very smelly old lady at Mass, the man with the bowel problem that leaves him smelling of faecal material, the man in the wheelchair who makes involuntary groans, the gurgling infant, the devout alcoholic who needs a swig of vodka half way through Mass to stop him shaking...are all behaving appropriately.
I have been in a very delicate state this last few months, I have needed to be at Mass and receive the sacraments. Can you imagine how upsetting it can be when you don't feel like you've been to Mass because children and their parents seem to have no understanding of the need for reverence, and that foucussed prayer needs a level of concentration that can not be obtained if some child you don't know is poking a Thomas the Tank Engine in your ear.
At that time the disciples came to Jesus, saying "Who is the greatest in the kingdom of heaven?" 2 And calling to him a small child, he put him in the midst of them, 3 and said, "Truly, I say to you, unless you turn and become like children, you will never enter the kingdom of heaven. 4 Whoever humbles himself like this child, he is the greatest in the kingdom of heaven. 5 "Whoever receives one such child in my name receives me;.."