Read Mark 3:27 Using Other Translations
No man can enter into a strong man's house, and spoil his goods, except he will first bind the strong man; and then he will spoil his house.
But no one can enter a strong man's house and plunder his goods, unless he first binds the strong man. Then indeed he may plunder his house.
Let me illustrate this further. Who is powerful enough to enter the house of a strong man like Satan and plunder his goods? Only someone even stronger—someone who could tie him up and then plunder his house.