If God is perfect and he knows what we need, why pray?
I answered a similar question on May 4th.
First of all you are speaking of only one form of prayer: that of petition; asking a favor of God. When asked how to pray, Jesus responded with the Our Father or Lord’s Prayer. It begins by acknowledging God as one whose very name is holy and acknowledging His Lordship by welcoming His kingdom and will over us. This is the prayer of adoration which is a matter of justice. We owe Him the acknowledgment of who He is. Then it goes into the prayer of petition in asking for our daily bread and sustenance.
Therefore, recognizing God’s sovereignty over us is the context from which comes the prayer of petition. So God is not a big vending machine in the sky, from which we expect the item that we have paid for with prayer. In praying, “Thy kingdom come; Thy will be done on earth as it is in heaven” we are untying all strings that we might be tempted to attach to the petition. In other words, we want to please the Lord more that we want to get our own way. So whatever we ask for, we ask for it only if it complies with His will for us. He knows what we need better than we do. So as you say, why ask? We ask as an expression of our need for Him. It’s actually an expression of humility.
To demand that He comply with our wishes is to imply that we know better than He, who is the creator and sustainner of all that is—or at least that we are more compassionate. In becoming incarnate and suffering and dying at the hands of men whom He created from nothing in order to demonstrate His unlimited divine love in a human way that we can understand, He has shown us what compassion is and how the power of love overcomes evil. It does so not by might, but by suffering with.
It behooves us to recognize that we do not see the whole picture. We are not His equals. Simply because we don’t understand some things, doesn’t mean that they are not understandable. It just shows us that we are limited in ways that He is not!
Fr. Vincent Serpa, O.P.