Why can Christians get demonised? Because transgression of the law lifts the protection of God from us.
Demons know this and they also know the Bible back to front. Effectively, demons are lawyers. They are experts on the word of God, which is why we have to know the word of God, to make sure we don’t trip up:
We stand on the word of God:
Psalm 119:114 King James Version (KJV)
114 Thou art my hiding place and my shield: I hope in thy word.
God is our shield:
Proverbs 30:5 King James Version (KJV)
5 Every word of God is pure: he is a shield unto them that put their trust in him.
The word of God is built up little by little:
Isaiah 28:10 King James Version (KJV)
10 For precept must be upon precept, precept upon precept; line upon line, line upon line; here a little, and there a little: