The UC campuses have many more well qualified applicants than can possibly be accommodated. Anywhere from a third to half must be rejected, and it is only fair to give preference to students who can demonstrate that they are most likely to succeed. There are several ways for students to demonstrate that they are qualified. Very high test scores are one, special exemption is another, and there are other ways for transfer and nontraditional students to get in, but the easiest path for freshmen is to get good grades in a UC-approved core curriculum in high school.

UC takes the approval process very seriously: it examines the textbook, the syllabus, any supplemental materials, sample lesson plans, and so on, to determine that each approved class actually teaches the material UC wants its incoming freshmen to know, at a college-prep level, accurately and completely. Students who have not demonstrated that they know this core material (because they didn’t bother to take the approved courses, or because they were home schooled) can still get in using the other pathways, although students relying on test scores alone must have higher test scores than students whose grades also demonstrate that they actually learned something in high school.

One could argue that this arrangement is unfair to home schooled students, but as you pointed out, the quality of home schooling is hugely variable, and UC has no way to tell which parents have provided a good education. It is important for a university to have a student body with diverse interests and backgrounds, but it benefits neither UC nor the students themselves to accept unqualified students. In principle and in effect, UC’s requirements are no different from an employer giving preference to a job applicant who presents evidence of actual relevant job experience over one who scores well on an aptitude test, but doesn’t present evidence of relevant job experience.

UC has no intention of closing its alternative paths to admissions, and Calvary Chapel’s students can use them even if they haven’t taken the proper coursework, just like any other applicant. Alternatively, a Calvary Chapel student can sign up for the appropriate number and kinds of UC-approved courses (the school has sufficient approved courses to offer students some choice while still fulfilling the requirements). What Calvary Chapel and its students can’t do is substitute unapproved Bible Study classes for the required science, history, and other academic classes, and expect a world-class secular university to go along with it. One has to wonder at the sheer hubris that leads them to file this lawsuit.