Seems odd. Lots of Court decisions on this stuff.
If students at this High School created a club for God or Christ and it was open to everyone it would have to be recognized by the School. The students could then display a flag.
The parents would not be allowed to though.
A School District cannot bar students from exercising their religious or cultural rights in school clubs as long as they are tolerant and open to everyone that wishes to join.
Accurate stuff.