Matthew 10 32 Whosoever therefore shall confess me before men, him will I confess also before my Father which is in heaven. 33 But whosoever shall deny me before men, him will I also deny before my Father which is in heaven. 34 Think not that I am come to send peace on earth: I came not to send peace, but a sword. 35 For I am come to set a man at variance against his father, and the daughter against her mother, and the daughter in law against her mother in law. 36 And a man’s foes shall be they of his own household. 37 He that loveth father or mother more than me is not worthy of me: and he that loveth son or daughter more than me is not worthy of me. 38 And he that taketh not his cross, and followeth after me, is not worthy of me. 39 He that findeth his life shall lose it: and he that loseth his life for my sake shall find it. 40 ¶He that receiveth you receiveth me, and he that receiveth me receiveth him that sent me.
Householdfoe is a family member that is your worst enemy. This is talked about in verse 36 and also in verse 35 and verse 37.
(Micah 7:6 [KJV]) For the son dishonoureth the father, the daughter riseth up against her mother, the daughter in law against her mother in law; a man’s enemies are the men of his own house.
The idea of a household foe is also in the old testament.
Matthew 16:23 But he turned, and said unto Peter, Get thee behind me, Satan: thou art an offence unto me: for thou savourest not the things that be of God, but those that be of men.
Satan can enter people.