This is just another example of wishy washy, liberal do-gooders putting their wrongheaded idealism before the safety of others, in this case the staff and students of the school. Although it sounds all nice and Christian and such, there are many possible situations in which God should, most definitely, be excluded from the classroom. For example, if God bullies the other students or consistently disrupts lessons with unruly behaviour. Such actions should result in a lengthy suspension, if not with permanent exclusion. Worse still, and certainly reasons for permanent expulsion, would be if God was caught pushing drugs or carrying a knife, or even a gun on school premises.
But, of course, the most obvious reason to exclude God from the classroom applies if the school in question is a Church of England school. If God cannot provide a letter from his vicar stating that God is a regular attender at his local Anglican church then there is no way he should get in. It is simply not fair for God to claim special circumstances and buck the system whilst the parents of other would-be students have to put so much effort into lying and cheating in order to get their little darlings into the school of their choice.