The fact that you are "qualified" to teach literally any course with any masters degree regardless of the relevance of your major is proof of that.
Just to clarify, that is only the case for elementary education. In middle school and up you have to have a degree in the subject (or at least something specific like " education") and pass the subject Praxis in order to be qualified to teach it.
Anyone who got an A in the course in question is qualified to teach it.
That's the kind of attitude that leads to terrible teachers. It really is not that easy. What do you think they do for two years in graduate school? Pedagogy is not a simple subject, and just because you know the material does not, in any way, mean that you can be an effective teacher. Also, if you think passing the course, or even excelling at the course, gives you the necessary content knowledge to effectively teach it, you are terribly mistaken. To be a really good teacher you need to have mastery of the entire discipline so that you understand where every class fits into the overall tableau. Not to mention the simple case of a student asking you a question that's not in the textbook (which is most of them).
1 + 1 = 3, for large values of 1.