LB, sometimes Frum people davka go to catholic colleges since there are less pritzus issues (which is more of a concern than avoda zara issues since the person is much more likely to be affected by them).
Amongst other things, I think they are usually not co-ed which of course, makes a tremendous difference.
Also, one of the big problems in a secular college is that fact that you end up becoming part of a chevra of Jews who are less religious than you are, and Frum Jews are much more likely to be influenced by other Jews (especially religious ones) than they are by Catholics.
And it’s not like you have to take any religion courses. My impression is that you take the same classes you would take in a regular college.