One definition of "acme" is "the top or highest point; the culmination." Christian Science is the ultimate, the culmination of Christianity, because it teaches scientifically how to live a Christian life.
Our Leader, Mary Baker Eddy, states in "Miscellaneous Writings" (p. 252): "Christian Science is not only the acme of Science but the crown of Christianity. It is universal. It appeals to man as man; to the whole and not to a portion; to man physically, as well as spiritually, and to all mankind."
Many years ago Christian Science appealed to a young student of this Science when he was confronted with a physical disorder which seemed very real to him and extremely terrifying. In spite of faithful efforts by Christian Science practitioners, the physical manifestation seemed to grow worse. At this point a friend urged him to rely upon a medical, rather than a Christian Science, practitioner.