However that is very different than describing a non-Christian person or group as anti-Christian. Do we call all people that are not Jews, anti-semites????? Of course not.
It connotes and, for all intents and purposes, means strong oppostion to or hatred for.
It would be utterly absurd to consider all things not Christian to be Christian haters. Thus the term anti-Christian, to most people, is understood to be a case of hatred, prejudice, vengeance toward, etc. and it does not apply to the majority of non-Christians.