I cannot see this as a situation in which it would be fine to have Christian prayers (or any other prayers) in schools, no matter how limited or extensive diversity is in this country. This is not a theocracy. Those who wish to transmit Christian values to their progeny are free do so at home, as I am free to transmit Jewish values to my offspring and as all others are free to do as well.
I have a friend who works for state government, and his office begins the day with a prayer. He is afraid to speak out against this because of a fear that he will lose his position. Now, if an adult is intimidated into praying every morning, imagine what it would feel like to be a child, forced to say the prayer of another faith or suffer the consequences of being singled out as the "other."
Unless and until this is a theocracy and our First Amendment is suspended, I cannot see any argument for prayer in a public school.