The Bible asks us to resist the devil and he will flee (James 4:7) but Martin Luther the great protestant reformer says that the best way to resist the devil is to insult him. In his ego and pride he will not be able to stand being insulted by a human. What will insult him is the finished work of Jesus on the cross. E.g. telling him,” Jesus has stripped you of all your powers and you are now only a paper lion”. By saying this with faith you can inflict intense insult on him. If you are going through a mental, emotional or physical struggle that is tormenting your mind you can always say, “Jesus will win in this struggle and you will lose because you are a defeated foe’. When you are fighting a mental or emotional struggle in your mind which the devil took years to build in your mind, he can voice to you in your mind saying that you are not a child of God by making you fall into the habit many times. He can discourage you and try and convince you that deliverance in impossible and that you have run beyond the scope of freedom. He may even drag you to the point that you are not saved and you will go to hell if you died now. You need to call these statements as his lies because the bible says that he is a liar and father of all lies (John 8:44). You need to tell him that Jesus loves you and so soon you will be delivered from that bondage. You should confess saying, “I will not die but live, and will proclaim what the LORD has done” (Psalm 118:17).
A friend of mine was addicted to drinking alcohol for many years. Even after he got saved his un-renewed mind fell into drinking many times. But each time he fell he would shout at Satan saying, “You will lose. Soon I will come out of this habit because he who is in me is greater than he who is behind this habit” (1 John 4:4). That junk that was accumulated in him over the years took some months to go but my friend held on to the confession and after his deliverance he says, “I don’t know how it left me but it left me. I no longer feel like doing it”. Friend! Deliverance is a process but you will surely win in the end. So friend don’t get discouraged that the devil is defeating you so many times and making you fall into it. Just get up every time and confess the truth that you will be soon free from the power of the bondage. As soon as he pushes you down he will immediately attack your mind saying,” You have no hope. You have run beyond the grace of God to save you. God is angry with you. You have to try your best to come out of it. (If you believe this lie then you will take upon yourself something that is beyond your power to break and get discouraged and even depressed). You rather have to say, “Jesus has paid the cost on the cross for me to get total freedom from this bondage and so I will receive the freedom”. You should read the Bible, read some books written by authors experienced on the subject, meditate on the power of the finished work of Christ on the Cross. The Holy Spirit will come to your help (Romans 8:26) in bringing to remembrance the truths of Christ in your thoughts which mixes with the faith in your heart and comes out of your mouth as words of power and you will win.