The admission is based on its entrance test as you can go through the information provided by the officials about its eligibility -

"Basic eligibility for the programme is a pass at the +2 level (Karnataka PUC / ISC / CBSE / NIOS / State Boards) Examination from any recognised Board with a minimum aggregate of 50% marks in Physics, Chemistry, Mathematics. Candidates should have studied Mathematics, Physics and Chemistry at Class XII level and obtained a minimum of 50% marks in Mathematics. Students pursuing International curriculum must have AIU approval and must obtain a grade of not less than 'C' or its equivalent. Candidates writing the +2 examinations in March-May 2018 may apply with their class X and XI marks".

You can check the admission process and selection process below -

Christ Univerity Admission Process

Christ University Selection Process

Good Luck!!!