Christian belief begins with the presumption of an omniscient God, which is based on extrapolation of the physical evidence of the nature of the universe: the evidence is insufficient to prove nor disprove with certainty, which is why one may have faith in a God, or have faith that the universe is as it is totally by chance.
The believer, by implication of the acknowledgement, has to believe that this god also knows the wants, feelings, needs, desires, intents and goals of the believer. So you have the believer and the believer's omniscient god as two entities, with no need for any "lines of communication / petition" (a.k.a prayer) between them, due to the quality of omniscience.
This is not true, on at least two levels. First, while the Christian believes that God already knows what we need before we ask, the Christian also believes that God commands us to ask--not for God's benefit, but for our benefit. For example, I already know most of my daughter's needs; does that mean she does not need to ask me, not for my benefit, but for hers?
Second, as in the quote above, prayer is not only petition, but communication--or, to be more accurate, communion. My daughter not only talks to me; she talks with me, a two-way communication, not only for the purpose of sharing information, but for the greater purpose of sharing relationship. The most important aspect of prayer is not what we say to God, but what God says to us: God already knows our needs, but we do not know the extent of God's nature or God's will, and the more we can experience that communion, the stronger our relationship to God.
Therefore, your dual assertion...
What does this render prayer into? Redundant nothingness. And religions that demand it? Self-contradictory nonsense. Enjoy your weekend!
...is twice incorrect. Prayer is the essence of a communicative communion with God, where we are given the opportunity not only of expressing our needs to a God for our benefit, but also of experiencing a dialogue that is a portion of a sensory and extrasensory communion. And there is therefore no self-contradiction. Whether it is nonsense or not depends on whether my "bet" that there is a God who desires a communal relationship with humans is accurate, or that your "bet" that there is no God is accurate. My experience, along with the nature of the universe itself, leads me to conclude that my "bet" is the accurate one. Which, by the way, is why I will indeed enjoy my weekend, and the eternity of which it is a part: not because I am wonderful, but because God is wonderful. And so can you.
She wouldn't need to ask you if she believed you knew everything running in her mind. Since you don't, and since she doesn't believe so either, she has to ask you. If she truly believed you knew everything running in her mind as well as she did, then neither of you would find any purpose or meaning in asking. Because the need is invalidated by omniscience. Do you ask your heart to beat at X Hz when you are performing a strenuous activity? No. Would you enjoy asking your heart to beat faster, even though you believe your heart knows what it has to do better than you do? You wouldn't, unless you were insane (compare this with the previous comment of mine, the part about the pertaining activity being nonsensical).
Second, as in the quote above, prayer is not only petition, but communication--or, to be more accurate, communion. My daughter not only talks to me; she talks with me, a two-way communication, not only for the purpose of sharing information, but for the greater purpose of sharing relationship. The most important aspect of prayer is not what we say to God, but what God says to us: God already knows our needs, but we do not know the extent of God's nature or God's will, and the more we can experience that communion, the stronger our relationship to God.
Your faith in your god to know your heart in and out, your intents and feelings, renders unnecessary the need for this mental / verbal / physical communication because by the repercussions of your faith, you ought to be 'spiritually' connected, and believe that you are so, whose lines of communication are superior to anything you do as a substitutionary activity to pretend to give a physical aspect to this 'communication'. Since a believer believes this to be the case, the unnecessary and self-contradictory nature of prayer becomes self-evident. To put it in simpler words, does the faith of a believer weaken when the believer falls into a coma? What about when the believer is in subconscious states, such as during deep sleep? If the answer is no to either, then my point remains validated.
At best, you can plead for a deistic god with your arguments, no more. The type that does 1 Samuel 15:3 is totally repulsive to me. Add to that, the prayer fluff, and the falsehood becomes unavoidably evident. Do you find this verse difficult to accept, even if you eventually do?
Oh, and I enjoy my weekends. My weekdays, too. After all, we live only once, and eternity is a fantasy. About half of all natural conceptions end up in spontaneous abortions where the mother isn't even aware of it, usually. Such is the nature of life.