What is prayer of petition?
Prayer of petition is born of the awareness of our need. God has every intention of giving, but only to him who asks, so as not to give something to one who would refuse to take it.
from St. Augustine Answers 101 Questions on Prayer by Fr. Ermatinger
For a moment, let the image of the door in scripture be pondered. From Revelation 3:20, there is the image of Jesus knocking upon a door of the individual’s house. From Luke 11:9-10 the image is of the individual knocking upon the door of the Lord’s house. In as much as the action of knocking is important, so too is the existence of the door. The door implies a separation, a barrier, a need to be overcome. Communication is made difficult between the individual and God. In the image of Jesus knocking, we find the individual locked within, unaware of his need; it is the knocking of Jesus upon the door that reveals this need. In the knocking of the individual upon the door of the Lord’s house, he finds that he cannot simply go into the abode of his Lord, but is in need of his Lord to come to him. The barrier reveals the need.
What is this door? It is the twofold separation between man and God; due to man’s creatureliness and God’s divinity, and due to man’s falleness existing in a state of sin below the fullness of his nature. In both of these images, man is on a different side of the door. He is outside of the Lord’s house while at the same time locked in his own. It is man’s response to this double door that unites both images. Confronted by this barrier of the door, becoming aware of his need, he pleads to the Lord who stands on the other side, “Come to me.”
Herein is what the prayer of petition is: The asking of God for a need that cannot be taken from God but that which only God can fulfill.
God can fulfill our needs, but will He? There is the shut door, after all. Yes. In both images, our Lord promises and reassures us that He will indeed come if He is but petitioned to come. He knocks that He might be beckoned to enter. He “sleeps”, that He might be beckoned to come hither. Time and time again, He promises, ‘If Isreal would but only call upon the name of the Lord’. So He will come to those that will to call out to Him. And that is the key to the door; the will to do so. We must will to give up our will: To will to not be self-sufficient behind our doors, to will to depend upon our Lord for our needs. To will to ask Him to come in, to will to ask Him to come out to us, so that He, by His presence, shall fulfill our need.