If the admissions committee agrees, you will be asked in for an interview. The final decision to accept you into the college comes as a result of the faculty-conducted interview. Even if you have the minimum grade point average to apply, you may not be accepted. Some areas like Social Studies are so crowded that you really need to stand out to be competitive. Your grades need to be strong in the content area you wish to teach.
Grades show more than just content mastery.
They illustrate that you have developed the needed skills to be a successful learner - the same skills you will need to teach students. Another crowded field is Elementary Education. You need to state in your career objective why you think you will stand out - strong grades, excellent references, willingness to relocate, willingness to teach in urban centers and other areas where teachers are needed. Faculty references can be from a university or high school faculty. If you are going to teach in a subject area, it is best to have a university faculty.