If the students knew it was a Catholic college, perhaps they could have applied to a different one instead. That there should be religous schools or colleges in the first place is an important issue, in a society which should not allow discrimination of any sort. But while there are still such establishments, which are not against the law, then it is understandable that these should want to encourage those with a similar philosophy to their own to be students. Although religious groups from different faiths are allowed, theoretically, the three monotheistic religions are supposed to worship the same god, but atheists obviously worship no god. Believers are much more accepting of believers from different faiths than they are of those with no faith at all.