According to the Washington Post, 92% percent of America answered that they believed in God when asked. However believing and knowing God are two totally separate things. Knowing God consist more than just believing that he exists, but actually having an interest in obeying His commands, giving Him glory and worshiping Him for life. Calvin writes on this matter;
By the knowledge of God, I understand that by which we not only conceive that there is some God, but also apprehend what it is for our interest, and conducive to his glory, what, in short, it is befitting to know concerning him. For, properly speaking, we cannot say that God is known where there is no religion or piety. I am not now referring to that species of knowledge by which men, in themselves lost and under curse, apprehend God as a Redeemer in Christ the Mediator. I speak only of that simple and primitive knowledge, to which the mere course of nature would have conducted us, had Adam stood upright. For although no man will now, in the present ruin of the human race, perceive God to be either a father, or the author of salvation, or propitious in any respect, until Christ interpose to make our peace; still it is one thing to perceive that God our Maker supports us by his power, rules us by his providence, fosters us by his goodness, and visits us with all kinds of blessings, and another thing to embrace the grace of reconciliation offered to us in Christ. Since, then, the Lord first appears, as well in the creation of the world as in the general doctrine of Scripture, simply as a Creator, and afterwards as a Redeemer in Christ,—a twofold knowledge of him hence arises: of these the former is now to be considered, the latter will afterwards follow in its order. But although our mind cannot conceive of God, without rendering some worship to him, it will not, however, be sufficient simply to hold that he is the only being whom all ought to worship and adore, unless we are also persuaded that he is the fountain of all goodness, and that we must seek everything in him, and in none but him. My meaning is: we must be persuaded not only that as he once formed the world, so he sustains it by his boundless power, governs it by his wisdom, preserves it by his goodness, in particular, rules the human race with justice and Judgment, bears with them in mercy, shields them by his protection; but also that not a particle of light, or wisdom, or justice, or power, or rectitude, or genuine truth, will anywhere be found, which does not flow from him, and of which he is not the cause; in this way we must learn to expect and ask all things from him, and thankfully ascribe to him whatever we receive. For this sense of the divine perfections is the proper master to teach us piety, out of which religion springs. By piety I mean that union of reverence and love to God which the knowledge of his benefits inspires. For, until men feel that they owe everything to God, that they are cherished by his paternal care, and that he is the author of all their blessings, so that nought is to be looked for away from him, they will never submit to him in voluntary obedience; nay, unless they place their entire happiness in him, they will never yield up their whole selves to him in truth and sincerity.
John Calvin, Institutes of the Christian Religion (Bellingham, WA: Logos Research Systems, Inc., 1997).