There's no single "pass mark" for Holy Childhood. "Holy Childhood" refers to several things, most notably the Pontifical Society of the Holy Childhood, a Catholic organization. This organization doesn't have exams or grades with pass/fail marks.
If you're referring to a specific school, exam, or program using the name "Holy Childhood," you'll need to specify which one. The passing grade will vary depending on the institution and the specific assessment.