What if you are a Christian and someone attacks you after you walk away from them? Should you retaliate back or just take the assault? Most would just fight back. I want to know if it's wrong in God's eye to defend yourself?
One does not retaliate, that would be vengeance. "If it is possible, as much as depends on you, live peaceably with all men. Beloved, do not avenge yourselves, but rather give place to wrath; for it is written, "Vengeance is Mine, I will repay," says the Lord" (Romans 12:18-19). Vengeance is left for those in authority to carry it out, and chiefly that is the Lord, though He has given the government a role in this as well. "For rulers are not a terror to good works, but to evil. Do you want to be unafraid of the authority? Do what is good, and you will have praise from the same. For he is God's minister to you for good. But if you do evil, be afraid; for he does not bear the sword in vain; for he is God's minister, an avenger to execute wrath on him who practices evil" (Romans 13:3-4). Therefore, if someone attacks you, you do not plot how you are going to attack him back later. See "Vengeance."
However, this does not mean that a Christian cannot defend himself while being attacked. See: "The Bible and a Gun." A Christian doesn't look for a fight or cause a fight, but he can stop a fight.