The Bible tells us that we are not just to pray, but rather to pray believing. If we are specifically told to believe when we pray, then it must be possible to pray and not believe. Not all prayer brings results. Only believing prayer moves God and receives from Him.
But let him ask in faith, nothing wavering. For he that wavers is like a wave of the sea driven with the wind and tossed. For let not that man think that he shall receive any thing of the Lord. James 1:6, 7
All of the world’s religions exhort men to pray, but it is only the Bible that requires men to believe what they pray. This is the radical concept of the Bible – the requirement of actually trusting God. This was first exhibited in the Old Testament, and further developed in the New Testament – the absolute necessity for one to believe when one prays. Other religious systems are content with the motions of prayer, but the true Living God requires that we maintain a relationship with Him and that we trust Him.
Therefore, I say unto you, whatsoever things you desire, when you pray, believe that you receive them, and you shall have them. Mark 11:24
Believing takes the emphasis off of prayer itself, and puts the emphasis entirely on God Himself. It is all about Him and His faithfulness. The Bible does not teach is to rely on prayer alone. It teaches us to rely on Him. Only when we can fully rely on Him can we fully pray believing. We are to believe Him first, and then express that belief in prayer. The faith must be in the heart before the prayer comes out of the mouth.
But what does it say? “THE WORD IS NEAR YOU, IN YOUR MOUTH AND IN YOUR HEART” — that is, the word of faith which we are preaching, that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved; for with the heart a person believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation. Rom 10:8-10