The most relevant qualification necessary for a Mental Health Counselor among the options you provided is knowledge of psychology and related books and resources.
Mental Health Counselors typically hold at least a master's degree in counseling, psychology, or a related field, which provides them with a strong foundation in psychological theories, therapies, and practices. They also often have access to various resources and literature in the field to continue their education and stay updated on best practices.
While understanding of religious traditions or history can be beneficial in some contexts, the core requirement revolves around knowledge of psychology.