The story of the Gerasene demoniac (Mk 5:1-20) is so intrigue that scholars in the past have done their best to apply various methods to analyzing it, and have come to some insightful findings. In this study, we interpret the story through extrinsic analysis and intrinsic analysis, by using the method of ideological criticism. Extrinsic analysis allows us to examine the socio-political and economical structures under which the powers were generated and exercised, and thus to see what is the mainstream ideology and the ideology advocated by the author. Secondly, as to the intrinsic analysis, the author encodes this unfavorable situation and reproduces a new ideology. In the encoding, the author links the spiritual world to the temporal world by insinuating the demon "legion" into the Roman troops, thus also linking theological thoughts to socio-political concepts. The author convinces the reader to believe in Jesus rather than any other ostensibly powerful people, groups, or self-styled gods by presenting his ideology that Jesus, the Son of God, is so powerful that he vanquishes all other evil powers, including satanic power, as well as the Roman empire's military power
