The Christian has put on the whole armor of God, he is filled with the strength and the power, and he has fought the battle in the evil day.
Then having done all, he is tempted to take off his armor. “I have gained the victory,” he says, “all is well.” Then, taking off his armor, he lies down on his bed.
“No,” says the apostle, having done all—to stand!” Go on standing. You are always on duty in the Christian life, you can never relax. There is no such thing as a holiday in the spiritual realm.
Martyn Lloyd-Jones in Christian Soldier, quoted in Spiritual Warfare