Double-Edged Sword studies how the literati of the May-Fourth Movement in the early 20th century, such as Chen Duxiu, Xu Dishan, Luxun and Maodun, understood the Christian literature. The author points out that those literati were not only interested in Christianity topics, but also valued the belief of Christianity positively. The author finds that some of them criticized Christianity, but the criticism was constructive. Double-Edged Sword is an important reference book for understanding the development of Christianity in modern China.