First off, If you read these verses, the "strong man" is a figure for Satan.
And this thread is about war not houses, two different subjects.
OK, you have me there...
So, the only strong man in our lives is satan?
And, we are weak and powerless and expected to lay down our lives for a common thief?
Your choice... Not mine...
Try this instead:
Mat 24:43 But understand this: If the owner of the house had known at what time of night the thief was coming, he would have kept watch and would not have let his house be broken into.
Luk 12:39 But understand this: If the owner of the house had known at what hour the thief was coming, he would not have let his house be broken into.
How would he have prevented the break-in?