Why we pray
I love the Lord, because he hath heard my voice and my supplications. Because he hath inclined his ear unto me, therefore will I call upon him as long as I live. Psalm 116:1-2
In these two verses, the psalmist expresses his love for the Lord. He is grateful for how God has answered his prayers. And as a result, it encourages him to pray even more.
But there are a number of precious truths embedded in the reality that God is a God who answers prayer. And these realities are a powerful encouragement for us to be praying people.
First of all, there is the reality that God is sovereign. What we mean by this is that "our God is in the heavens: he hath done whatsoever he hath pleased" (Ps. 115:3). There is no way we could have any confidence that God could answer our prayers if we did not first believe that God is in control and that there is no circumstance beyond his power and his ability to change. Thank God for his sovereignty.
Second, there is the reality that God is good. Just because God is sovereign does not by itself give us any confidence that he would answer our prayers. But God is not only great, he is also good. He is righteous and holy and he will always do what is right (Gen. 18:25). When we cry out to him for justice, we know that he will hear us.
But God could be great and good and yet still justly leave us to ourselves. So I'm also thankful for the reality that God is gracious, that he is a God who saves sinners: "This is a faithful saying, and worthy of all acceptation, that Christ Jesus came into the world to save sinners, of whom I am chief," wrote the apostle Paul (1 Tim. 1:15). He is a Father to those whom he saves and encourages us to call upon him in that capacity (Mt. 6:9).
Finally, I'm thankful for the reality that God is wise. "O the depth of riches both of the wisdom and knowledge of God! How unsearchable are his judgments and his ways past finding out!" (Rom. 11:33). This means that he not only can and not only will answer the prayers of his children, but that he will do so in the best and wisest of ways.
Why do we pray? We pray because God is sovereign, because he is good, because he is gracious and loving, and because he is wise. Of course, we must recognize that it is not true that God hears the prayers of everyone, for Scripture repeatedly asserts that the prayer of the wicked is an abomination to the Lord (cf. Prov. 15:8, 29). What puts us in the category, not of the wicked, but of the righteous? It is actually not our goodness, but the goodness and righteousness of God freely and graciously given to those who trust in his Son, who died for his people so that they too can say, "I love the Lord, because he has heard my voice and my supplications."