I don't believe in God but i find thinking about the logic behind religion interesting to think about, and i cant see any good reason why a believer should have to pray to God if God is supposed to know everything including what they are thinking at all times.
It's important to recognize that prayer, like other forms of communication, is embedded in an attitude of the speaker. Rarely is a communicative act ever a simple relaying of information. Instead, communicative acts serve implicit and more critical functions. For example, my relaying the information of my previous heart problems to my doctor serves not only as an act of literal communication but as an act of therapy. My plead to a doctor to assist me not only relays to her my current status but opens a door where I myself, through my communication, am welcoming her to help me.
So while it is true that there is a certain redundancy in performing a communicative act with an all-knowing entity since said entity already knows what it is we are trying to communicate, the redundancy really only holds a significance considering the literal information being relayed. What saves most communication from being redundant is that it fosters community. Prayer is no different. The theist would say that prayer's main function is not to relay information to God, but to welcome God's intervening in our lives, specifically through the attitude of pleading (St. Augustine states "prayer is a petition" (De Uni., vi. 14)).
It is also important to keep in mind that prayer isn't necessarily to God alone. As St. Aquinas states:
Prayer is offered to a person in two ways: first, as to be fulfilled by him, secondly, as to be obtained through him. On the first way we offer prayer to God alone, since all our prayers ought to be directed to the acquisition of grace and glory, which God alone gives, according to Psalm 83:12, "The Lord will give grace and glory." But in the second way we pray to the saints, whether angels or men, not that God may through them know our petitions, but that our prayers may be effective through their prayers and merits (ST II Q. 83).
Aquinas is not only restating that prayer serves a petitionary purpose (which would exempt prayer from your charge of redundancy), but he is also presenting a more global perspective of prayer (i.e., as an essentially communal act that is performed in the presence and for the persuasion of both angels and saints who are not all-knowing).
Another Objection to Prayer
A more potent objection to prayer would be to question the logic behind suggesting that God can become 'closer' to a person through prayer. Isn't God omnipresent? But even here I think the theist has the resemblance of an answer. It is not God who needs to become closer to man but man that needs to become closer to God. This logic still might be questioned if we think of 'closer' in a distance sense, which presupposes that there is some single, absolute space between the two limited points. But for the theist, they normally adopt a distinction between God and man comparable to the difference between actuality and potentiality, or absolute and relative, in which case any 'distance' is not one between equals but one between a master and a servant. As such, the act of becoming 'closer' to God is similar to an effect becoming actualized, or darkness being lit. When thought about in this way, the act of becoming closer does not need to imply a limitation to God's power nor a redundancy in light of God's power.
Assuming you are referring to 1) an omni-potent god, and are looking for 2) a non-hard-determinism answer
Omniscience, a property of the Islamo/Judeo/Christian deity, is the state of knowing all. Will, or free will, is a paradox; perfect foreknowledge excludes the possibility of volition. One explanation is that although the universe is determined in advance, and major human events are determined, at an individual level there is spiritual wiggly-room in which volition is possible, and in most cases permitted (baring instances of direct intervention to preserve the major human events: consider the hardening of the heart of the Pharaoh).
The experience between the ears of humans is exempt from the usual causation of the universe because of the metaphysical (non-physical) nature of the soul, which transcends the physical world.
Given this, prayer is an act of volition possible only by those with a soul. The purposes of prayer are, in my simple understanding, grouped into four major themes:
worship/acknowledgement of the deity investigation of the nature of the deity request to the deity for intervention in the life of the individual supplication to the deity to forgive the failings of the individual
The first is pleasing to the deity, and is the purpose of creation of sentient species; the tri-omni deity creates knows itself, and all things, completely, and is perfect. This deity creates minds from itself that are incomplete in their knowledge, and thereby imperfect. The deity enjoys those minds realising and being awed by the existence and nature of the deity, and seeking to be aligned to the will of the superior mind.
The second is the attempt to learn the nature/desires/will of the deity in order that behaviour can be aligned to the appeasement thereof. It is motivated by the realisation of the nature of the deity, and the obligation/gratitude of having being created.
The third is either a request of favour, or more usually a request for guidance/support in the pursuit of an activity believed to align to the nature/desires/will of the deity. This can be a request for an essentially selfish reason, to succeed in a personal endeavour, when such an endeavour is contextualised as a striving to become a less-imperfect being by delevoping those abilities or capitalising on those opportunities that the individual finds gifted to them.
The fourth is apology for deviating from the will of god (either through inappropriate behaviour or lack of appropriate behaviour. Behaviour = action, thought, attitude)
Essentially, prayer is a combination of acknowledgement of the deity, a request for instruction from the deity, a request for support in those activities that the supplicant holds dear AND believes in alignment with the will of the god, and apology for failure to act on the will of the diety/ deviation from that will.
Regular and ritualised prayer, the lip-service prayer, is a mechanism that develops this way of viewing life: gratitude for that which is, hope for that which one desires, seeking permission for all action, deference to the moral authority of the deity; the positive association formed by the repetition and social importance (thanks to deity for this food/wedding/health/sporting achievement/etc) means that in times of crisis that cognitive pattern is available as a tool for problem solving. We turn to prayer in times of need, because we do it in times of plenty
Prayer should be for uplifting (the person, persons, society, .... the whole world etc.) from a 'lower level' to a 'higher'. If one can do this without praying, that is enough.
But that person must be a 'real seeker' in all its aspects. Many men who realized the Ultimate truth were not 'believers in God' at their younger days.
“All that is required to realize the Self is to “Be Still.”
.........says Ramana Maharshi. That means, prayer is not necessary even to realize the Self. But certainly prayer helps to pacify the mind and makes the process easier.
why a believer should have to pray to God if God is supposed to know everything including what they are thinking at all times.
From a higher level we can say the prayer is for the person who prays. It is not for reminding God of something.
If God knows what you are thinking at all times, why pray?
This question assumes a particular view of the nature of God, namely that God is a personal, transcendent being, exalted over and distinct from God's creation but communicating with that creation in various ways, knowing its prayers and responding to them by granting or denying them.
The question has clear point : prima facie it makes no sense to pray to God (for benefits to oneself or others, to seek guidance or whatever) when God by virtue of omniscience already knows our thoughts.
Suppose, however, that this is the wrong model of God. On an immanentist view, God is a presence in the innermost nature of human beings. Such a God is identifiable with our developing finite consciousnesses. It then seems a clear possibility that God does not know what we are thinking until we think it since God is not distinct from us.
If the immanenentist, or this imanentist, view is rejected, how might the question be tackled on the traditional, transcendent model of God ?
I suggest two lines of approach.
Prayer is not just thought but an act of reverence and devotion, an exercise of faith through free will - the fruit and evidence of genuine trust in God. God may know that we will pray but we add to the transaction, the communication, by this exercise of faith. If God knows what we are thinking, we still contribute a demonstration of trust.
God may want, and be able, to create all (logically possible) goods. If I pray for my friend's recovery from illness, that recovery may have been part of God's plan from all eternity, yet its goodness may be increased by my praying for it in sincere trust in God's benevolence.
Praying is a speech act. Speech acts are important to distinguish because there is a real difference between thinking something and doing something. You can think about how much you love your partner. You can tell your partner you love them. You can think to yourself that you will never betray them. You can think about promising to them that you will never betray them. But none of these are the same as actually making a promise to your partner that you will never betray them. You can't be blamed for breaking a promise you never made, and we treat people who've made us promises differently from those who haven't, whether that's in love, in business, or in politics. And that's why traditionally weddings have been such a big deal, because the act of making those promises is significant, and worth celebrating.
In the same way, thinking something, even thinking about praying, is not the same as praying. You can think about something you need or want. You can think about how your God can provide what you need or want. Your scriptures may even contain promises from your God that he will provide what you need or want, and you can meditate on those promises. You can think about how you are utterly dependent on God to provide all your needs. An omniscient God will know all these thoughts of yours. But none of them, individually or added together, can replace the speech act of actually asking God for your needs or wants (the speech act in prayer can be mental rather than verbal.)
Now this may seem like a pedantic thing for a God to care about, that even though God may know all your thoughts, and intend to do good for you anyway, that you have to actually ask him. Well I think that for most theists, especially Christians, this is connected to one of the other great mysteries of the relationship between God and humanity, that age-old question of free will vs God's sovereign determining will. Most theists are compatibalists - although we may not be able to explain how, humans truly have real independent wills, while at the same time God wills freely how the universe proceeds. If you can accept compatibalism, then I think you can accept that it can make a difference whether or not humans pray without implying that God changes his will based on what humans do. This may sound contradictory, but I think it is a sub-part of the broader compatibalism concept and flows out of it naturally.
Kant has an interesting argument about why prayer in a way is "wrong" or "misguided" (not absolutely, but to some extent...). This is from Religion within the Limits of Reason Alone and my loose reconstruction is as follows. Now, when we pray for something, we are praying for something evil, neutral, or good. God has no reason to answer neutral prayers and has a reason not to answer evil ones. But suppose we pray for something good. God already knows what is good and so has a prior reason to give us what is good. God does not need us to go and pray for what is good as such, then. Praying for something good doesn't make that thing more good or more deserving of being given.
Now prayer might have all sorts of nice side-effects on our side of eternity, granted, but it's not to be said that a person who does what is right and good but never otherwise prays, is "farther" from God than someone who does all sorts of right and good things and also prays. For on Kant's model of these matters, someone doing the right thing in the right frame of mind is as it were praying by that very doing. Truly good actions have a communicative function just as classical prayers do. There is, at were, a syntax of goodness whereby good actions become words, and sequences of good actions therefore become sequences of words, which go on to represent assertoric sentences (made of goodness!), and these ideal assertions are equivalent in value to verbal petitions (as prayer).