The thief comes only to steal and kill and destroy; I have come that they may have life, and have it to the full. John 10:10
A man comes back to his house and unlocks the door, only to find that his house has been broken into. His house is destroyed and he has been stolen from and he blames the thief. But is that not what a thief does, the thief is a thief because he comes to steal, to take. The thief was just being who he is. The man blames the thief but the truth is that he left a single window open. That one window was all the opportunity the thief needed and he took it. In fact, the one window made the thiefs job easy to get into the house.
This can be applied to our spiritual lives. If we leave one window open the thief, the devil, the world, will come and find that weakness and use it to enter into our house and take from us. We must make sure that our house is secure, no windows open, no doors unlocked.