On what grounds could I avoid studying religious studies in my school since they are taught from the Christian perspective?

Huzoor (rh): No, you should not avoid them at all. Study them and give them proper answers from Islamic point of view. Why should you avoid any other study unless you know the attitude and doctrines of other people? You cannot convince them of the truth of Islam. It is highly important that you learn everything that comes your way, which can be termed as rational knowledge.