In the books of the old testament we find references to our enemies an what we should do to our enemies...now the question arises who is my enemy.
in the new testament we find Jesus defining who is my neighbor from the parable of the good Samaritan when a lawyer questions

Luke 10:29 And who is my neighbour?

and Jesus taught him who his neighbor was through this parable:

Luke 10:36 Which now of these three, thinkest thou, was neighbour unto him that fell among the thieves?

and the reply was

Luke 10:37 And he said, He that shewed mercy on him. Then said Jesus unto him, Go, and do thou likewise.

now since we have the definition of neighbour we would seek to find out who our enemy is.
there are various psalms which talk about enemy...most of them talk about fighting our enemies.
are we supposed to fight our enemies since jesus commanded us not fight against our enemies

Romans 12:20 Therefore if thine enemy hunger, feed him; if he thirst, give him drink: for in so doing thou shalt heap coals of fire on his head.

but in the old testament we find hatred against our enemies

• Psalms 64:1 my voice, O God, in my prayer: preserve my life from fear of the enemy.
• Psalms 18:17 He delivered me from my strong enemy, and from them which hated me: for they were too strong for me.
• Psalms 42:9 I will say unto God my rock, Why hast thou forgotten me? why go I mourning because of the oppression of the enemy?
• Psalms 143:3 For the enemy hath persecuted my soul; he hath smitten my life down to the ground; he hath made me to dwell in darkness, as those that have been long dead.

so then the question arises who is my Enemy??????
Jesus answers that also.....

• Luke 10:19 Behold, I give unto you power to tread on serpents and scorpions, and over all the power of the enemy (Satan): and nothing shall by any means hurt you.
• Luke 10:18 And he said unto them, I beheld Satan as lightning fall from heaven.
  
• Matthew 13:39 The enemy that sowed them is the devil; the harvest is the end of the world; and the reapers are the angels.

so we see here the real enemy of mankind is Satan....and the way rid of the devil is demonstrated by the apostle Paul in the book of acts.when he encounters a girl with a demon of fortune telling.

Acts 16:18 And this did she many days. But Paul, being grieved, turned and said to the spirit, I command thee in the name of Jesus Christ to come out of her. And he came out the same hour.