If You Are Not With Him - You Are Against Him
Although Jesus came to bring the peace of God (John 14:27; Philippians 4:7), and peace with God (Romans 5:1), His coming also brought division: Think not that I am come to send peace on earth: I came not to send peace, but a sword. For I am come to set a man at variance against his father, and the daughter against her mother, and the daughter in law against her mother in law. And a man's foes shall be they of his own household. (Matthew 10:34-36)
Jesus divided all men into two battle camps. It is not possible to be neutral:
No man can serve two masters: for either he will hate the one, and love the other; or else he will hold to the one, and despise the other. Ye cannot serve God and mammon. (Matthew 6:24)
He that is not with me is against me... (Luke 11:23)
Jesus spoke of this great division in a story about two paths, one which was straight and narrow and one which was broad. He warned of the deception of Satan's broad path which many took (Matthew 7:13-14). Through the account of the rich man and Lazarus (Luke 16:19-31), Jesus removed the veil between life and death. He let men see the end result of choosing the wrong way.
Because He destroyed and exposed the works of Satan, Jesus was under assault throughout His earthly life. The enemy constantly tried to destroy Him or prevent Him from fulfilling the mission for which He had come. The moment He was born, an attempt was made on His life.
During His public ministry there were several plots on His life and at least one attempt which was aborted. He met the opposition of demonic powers, religious leaders, His own followers, and Satan.
When you align yourself with the plan and purposes of Jesus by accepting Him as your Savior, you become part of the army that wars against Satan. The purposes of Jesus become your purposes and this sets you in a tactical position of direct opposition to the enemy (Satan) and the satanic systems of the world.