[A time came when] I, not through indifference, but after mature consideration, ceased to pray every evening, as I had been in the habit of doing since childhood; because prayer seemed inconsistent with my view of God’s nature; saying to myself, either God himself, being omnipresent, is the cause of everything even of every thought and volition of mine and so in a sense offers prayers to himself through me, or, if my will is independent of God’s will, it implies arrogance and a doubt as to the inflexibility as well as the perfection of the divine determination to believe that it can be influenced by human appeals.
It’s a prima facie promising line of thought. Plausibly, the ostensible point of praying is to move God to act by calling His attention to injustices in need of correction. But because God is omniscient He already knows of the injustices that are in need of correction, and because He is omnipotent and omnibenevolent He has already moved to correct them. So prayers are not only pointless, but also, insofar as they presuppose that you’ve noticed an injustice God has overlooked, arrogant, as well.
One arguable response is that the point of praying is actually to give God moral permission to intercede on your behalf; absent that permission, His respect for your autonomy would keep Him from giving certain kinds of aid. (Of course, this means that other-directed prayers remain pointless and arrogant, given that you cannot waive others’ moral rights.)
It’s also worth observing that another promising line of thought culminates in justified bafflement at why Bismarck thought it appropriate to include these atheodic meditations in a marriage proposal.
Update: My mother suggested to me, in so many words, that another possible justification for prayer is that it is the religious equivalent of exercising your Due Process right to be heard. Presumably God, much like a State, makes decisions about the architecture of nature. It is thought that when a State makes (certain kinds of) decisions that affect us, we have a right, which we should be encouraged to exercise, to voice our concerns to the State. (We are equally encouraged even if we are concededly in an epistemically, and even morally, inferior position to the state.) Likewise, then, we should voice our concerns to God.
Of course, a corollary to the right to be heard is the right to notice. So, by calling attention to God’s deafening failure to communicate his intentions to us in plain, non-esoteric, prose, Mama’s response arguably functions better as a novel (to my knowledge) variant on the Problem of Evil than an apologia for prayer.