1 John 4:4 (NKJV)
"He who is in you is greater than he who is in the world."
The Bible doesn't say we won't have challenges and face attacks. What it does say is it shall not prosper against you. This is also followed by a tremendous promise that "This is the heritage of the servants of the Lord, and their righteousness is from me" Isaiah 54:17. So protection is your heritage, not because you do right, He protects you because your righteousness is from Him. Also note that the weapon has already been formed. So it is conceived, prepared, and directed toward you. However, the Bible commands us not to be afraid. For we know according to God's word that it will not prevail against us. And remember, it's not because of your behavior; it's because of your standing. We are firmly secured because of Christ's finished work.
With this knowledge we have the ability to pull down strongholds. So as we put the truth over our minds, we have confidence that God's word will direct and affect our thinking to victory that he has for us. Will you note the battle for your mind is not waged externally; our weapons are not physical or tangible. Our weapons are right thinking and believing and they are mighty! Through God's word we are able to pull down strongholds that have kept us limited, confused, and bound. Also strongholds cannot be destroyed with physical weapons. They must be taken down in Jesus name with right thinking. The devil can sow wrong thoughts in your mind, but he cannot control what you believe.
The encouraging part of this is that we go by what we believe, therefore, it has a direct impact on what we think. Lies can imprison you and bring about defeat, but God's word brings liberty. Jesus' word ...
"If you abide in My word, you are My disciples indeed. And you shall know the truth and the truth shall make you free".
John 8:31-32 (NKJV)