You can say prayers in your mind but doubt in your heart. At times God will answer such prayers as He did when Peter was in prison, scheduled for execution. The believers in Jerusalem were powerless to free him, so they prayed. When God released Peter, their reaction revealed the doubt in their hearts. They argued that Peter could not possibly be free, even as he stood outside knocking on the door!
Is it possible to be a “person of prayer” and yet not have faith? Is it possible to fool yourself into believing that because you ask God for help, you have faith in His ability to meet your needs? Is your faith so weak that you are surprised when God answers your prayer? As a child of God, you ought to expect God to answer your prayers. Do you ask God to do something without adjusting your life to what you are praying? If you are praying for revival, how are you preparing for its coming? If you are praying for forgiveness, are you still living with guilt? If you have asked God to provide for your needs, do you remain worried and anxious?
Ask God to increase your faith and then begin living a life that reflects absolute trust in Him. Out of His grace, God may choose to respond to your requests despite your lack of faith, but you will miss the joy of praying in faith.