Why pray if God is omniscient? Possible Duplicate:
  What is the purpose of Prayer?  




What the question says, why do people pray if God knows everything?
This is kind of like asking, "Why should you tell your Dad you love him if he already knows?" It's not about conveying information, it's about fellowship. God created us for fellowship with Him. We don't pray because God needs to be reminded of our needs, we are supposed to pray because we are to partner with Him to see His will be done. He choose not to force us to do His will, but that we are to choose to seek His will. Jesus told us to pray in this way:


  Pray in this way "Our Father in heaven, hallowed be your name. Your kingdom come, your will be done, on earth as it is in heaven. Give us this day our daily bread, and forgive us our debts, as we also have forgiven our debtors. And lead us not into temptation, but deliver us from evil." 


Prayer recognizes God as our Father, who is holy, and seeks to put our mindset in alignment with His.