Luke 10:17-20 (NKJV)
17 Then the seventy returned with joy, saying, “Lord, even the demons are subject to us in Your name.” 18 And He said to them, “I saw Satan fall like lightning from heaven. 19 Behold, I give you the authority to trample on serpents and scorpions, and over all the power of the enemy, and nothing shall by any means hurt you. 20 Nevertheless do not rejoice in this, that the spirits are subject to you, but rather rejoice because your names are written in heaven.”
Psalm 23:4 (NKJV)
4 Yea, though I walk through the valley of the shadow of death, I will fear no evil; for You are with me; Your rod and Your staff, they comfort me.
Isaiah 54:17 (NKJV)
17 No weapon formed against you shall prosper, and every tongue which rises against you in judgment You shall condemn. This is the heritage of the servants of the Lord, and their righteousness is from Me,” Says the Lord.
2 Chronicles 20:15b (NKJV)
15 Thus says the Lord to you: ‘Do not be afraid nor dismayed because of this great multitude, for the battle is not yours, but God’s.
James 4:7 (NKJV)
7 Therefore submit to God. Resist the devil and he will flee from you.
Ephesians 6:11-16 (NKJV)
11 Put on the whole armor of God, that you may be able to stand against the wiles of the devil.
12 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. 13Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand. 14 Stand therefore, having girded your waist with truth, having put on the breastplate of righteousness, 15 and having shod your feet with the preparation of the gospel of peace; 16 above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one.
2 Corinthians 2:11 (NKJV)
11 lest Satan should take advantage of us; for we are not ignorant of his devices.
1 Peter 5:9 (NKJV)
9 Resist him, steadfast in the faith, knowing that the same sufferings are experienced by your brotherhood in the world.
Revelation 12:11 (NKJV)
11 And they overcame him by the blood of the Lamb and by the word of their testimony, and they did not love their lives to the death.
1 John 2:13 (NKJV)
13 I write to you, fathers, because you have known Him who is from the beginning. I write to you, young men, because you have overcome the wicked one. I write to you, little children, because you have known the Father.
See more scriptures on being an Overcomer.