Many, because of their faithful attendance to a building or a creed, consider themselves religious. They imagine themselves close to God. The term is so often related spiritually that the basic meaning is seldom thought of.
Being religious is having a very devoted interest in something. An athlete is religious to training, a mother is religious to her children, a business man is religious to making a profit, an alcoholic is religious to drinking and so on.
Satan considers himself religious for he has a cause. He is religiously devoted to keeping as many as possible from taking Jesus seriously. He is religiously devoted to rendering ineffective as many believers as possible. He, too, is religious.
Be careful! Watch out for attacks from the Devil, your great enemy. He prowls around like a roaring lion, looking for some victim to devour. (1 Peter 5:8 NLT)