Job placement rates for graduates can vary widely depending on the school. Rather than searching for an average among Christian colleges (the data for which is limited), look for the rates on a school-by-school basis. However, job placement rates in general can be tricky to accurately determine, even from just one institution.
Many colleges will have the job placement rates of their graduates available to see somewhere on their official website (especially if the rate is high). All schools are required to be able to provide students with job placement rates in some capacity, however, there are little to no regulations on how the schools measure that information. Typically, some sort of job placement survey is sent to alumni and the data is skewed to only those who respond to the survey-often those who are most likely to respond are those who are proudly employed.
If the job placement rate is difficult to find on the website, get in contact with the admissions office or career services department of the school and ask what the rate is. Follow up questions that may help get a better understanding of the results are: how was the data collected? What does the school consider placement? When was the data collected? Is the data specific to any major, or is it general?