Notice, then, prayer must be in accordance with the will of God revealed to us. This is a great verse that gives us great confidence, that if we pray in accordance with God's own promises, he will do what he has promised. This, also, is a very good illustration of proper prayer, prayer in accordance with the will of God. Prayer is important, first, because God has commanded us to pray. It is through our prayer God meets our need.
Prayer is the ordained means of grace by which our needs are being met.
Secondly, there is a devil who is opposed to every Christian. Your enemy, the devil, prowls around like a roaring lion, looking for someone to devour. Resist him, standing firm in the faith. So another reason to pray is that there is a devil who is ever trying to defeat and devour us. Of course, this will not happen, because God loves us and is for us.