And when you pray, do not heap up empty phrases as the Gentiles do, for they think that they will be heard for their many words. 8 Do not be like them, for your Father knows what you need before you ask him.

In ancient anthropology all creatures are distinguished by the fact that they are in need of something at all times. This idea has played an important role in Greek philosophy, especially in connection with theories about the origins of human civilization. According to Diodorus Siculus 1.8.5–9, “need” was the teacher of primitive humanity in that it forced them to develop the arts and sciences in order to cope with these needs. There were further ideas on this topic.309 Perceived needs may be wrong needs, based on error or folly; preoccupation with wrong needs, which in truth may not be needs at all, may prevent people from perceiving their real needs. Whatever the case may be, there was widespread agreement in antiquity that only the deity can know what is truly good and, therefore, what our real needs are and how they can be met. As I have pointed out before, this view was accepted by large sectors of Hellenistic philosophy.311

They pray, not to inform the Father on matters of which he is ignorant, but to worship him

Some might object, “Then, why pray at all?” The objector, however, misses the point. Jesus was not condemning the outpouring of the heart to God, not even when of necessity such an outpouring contains a brief statement of certain facts already known to the Lord (see, for example, many of the Psalms). In fact, it is just because an earthly father or mother understands a child so thoroughly and knows its needs better than any stranger does, that the child will go with his needs to him and/or to her, which is exactly what loving parents want him to do. So, far more so, it is also with the heavenly Father (Ps. 81:10; Matt. 7:7, 8; John 15:7; Heb. 4:14–16; James 4:2). What Christ condemns is the spirit of fear and distrust, which causes pagans, who recognize no heavenly Father, to babble on and on, in the belief that otherwise their gods will not be thoroughly informed nor sufficiently placated to grant the requests.

Let Calvin answer your question: ‘Believers do not pray with the view of informing God about things unknown to him, or of exciting him to do his duty, or of urging him as though he were reluctant. On the contrary, they pray in order that they may arouse themselves to seek him, that they may exercise their faith in meditating on his promises, that they may relieve themselves from their anxieties by pouring them into his bosom; in a word, that they may declare that from him alone they hope and expect, both for themselves and for others, all good things.’1 Luther put it more succinctly still: ‘By our praying … we are instructing ourselves more than we are him.’2.