Believer's are in a warfare against the devil and his demons. The earlier we realize this and put on these weapons the better our chances of winning the heavenly race is sure and guaranteed. The bible admonishes the believer's to put on the whole armor of God in order to withstand the wiles of the devil. 
Finally, my brethren, be strong in the Lord and in the power of His might. Put on the whole armor of God, that you may be able to stand against the wiles of the devil. For we do not wrestle against flesh and blood, but against principalities, against powers, against the rulers of the darkness of this age, against spiritual hosts of wickedness in the heavenly places. Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand.

Having girded your waist with truth, having put on the breastplate of righteousness, and having shod your feet with the preparation of the gospel of peace; above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one. And take the helmet of salvation, and the sword of the spirit, which is the word of God; praying always with all prayer and supplication in the Spirit, being watchful to this end with all perseverance and supplication for all the saints{ Ephesians 6:10-18}.

An understanding that whatever negative character anyone around us displayed is influenced by the devil, will help us in the fight against the devil. Notice verse 11 says, For we do not wrestle against flesh and blood; our fight is not against the human being we are seeing but rather the spirit behind their actions. When Peter try to rebuke Jesus about his death on the cross , Jesus immediately rebuke the devil in Peter and not Peter, He said get behind me devil, this tells us that our war is not flesh and blood. The illustrates the forces we are fighting as summarized below;