For a number of years now it has been mandated in the Methodist Church that we offer communion to any child who wants to partake and whose parents or guardians agree.
The following is a very simple observation, not a reasoned argument.
The churches in our circuit are doing a review of congregational and circuit life. As part of this review process, we focussed last Sunday on the Beatitudes and we asked people to get into groups and answer two questions: 1) How does God bless me in this congregation and 2) How can this congregation bless others? ('Bless' was changed to 'make happy' for the children.)
The first item on the children's list was: 1) When we have bread and wine - to feel strength and God's spirit; 2) God wants everyone to come and bread and wine to help them.
These children are between the ages of 7 and 9. This is as great an 'argument' for children's communion as I can think of - along with 'Let the little children come to me' of course. And I have to say that I was blessed by reading these contributions!