Daniel Klein has written an essay on "Adam and God" published at the website for the American Institute for Economic Research. He notes that the scholarly interpreters of Adam Smith have disagreed about whether God, or a being like God, is crucial for Smith's ethics. He argues that "yes, a God-like being plays a central role in Smith's ethics." In making that argument, he believes that he is in agreement with a long list of Smith scholars, and I am on that list.
Whether I agree with Klein depends on resolving the ambiguity in his claim that "a God-like being plays a central role in Smith's ethics." This is ambiguous in two ways. First, does the "God-like being" exist independently of the human mind, or does it exist only as an anthropomorphic projection of the human mind? Second, must this religious belief "play a central role" in the ethics of all human beings, or is this religious belief necessary for the ethics of some human beings, but not all?
If Klein means to say that God as an anthropomorphic projection of the human mind plays a central role for some but not all human beings in Smith's ethics, then I agree. If some Smith scholars do not see this as Smith's teaching, it's because they fail to recognize that Smith was the last esoteric writer, and so they fail to distinguish Smith's surface teaching from his secret teaching.
Like David Hume in his Natural History of Religion, Smith explains religious belief as a natural psychological propensity for anthropomorphic projection of human mental experience onto the universe, so that human beings imagine that there are invisible spirits with minds like their own (see, for example, TMS, 163-64). And since human beings have moral sentiments and passions, they imagine that these divine beings have the same moral sentiments and passions. In this way, religion sanctions morality as divine law, and thus provides supernatural support for a natural sense of moral duty. A philosopher like Smith might then conclude that moral rules are "justly regarded" as divine laws. Even if he thinks this is only a noble lie, he thinks that it is good for us if most of us believe it to be true.
Klein rightly points to a passage in The Theory of Moral Sentiments (p. 215) where Smith speaks of the "man within the breast" as the "representative of the impartial spectator," and the impartial spectator is understood to be a single universal being, which, according to Klein but be a superhuman or God-like being.
But the thought in this passage is elaborated in another passage, where Smith says that human beings must consult "this inmate of the breast, this abstract man, the representative of mankind, and substitute of the Deity, whom nature has constituted the supreme judge of all their actions" (130). Notice here the equivalence between "the representative of mankind" and the "substitute of the Deity," and the suggestion that it is natural for human beings to imagine the Deity as the anthropomorphic projection of mankind.
In some previous posts, I have shown how Darwin and modern evolutionary psychologists have confirmed this insight of Smith and Hume that believing in God is a natural, almost inevitable, consequence of the innate propensities of the human mind as shaped by natural selection in evolutionary history.
Smith is also like his friend Hume in thinking that some human beings can be good without God--they can recognize moral law as enforced by natural human sanctions without having to believe this is a divine law enforced by supernatural divine sanctions. This supports Smith's liberal moral anthropology that does not depend on a transcendent moral theology.
The best evidence for this is in Smith's letter on the life and death of Hume--the Letter to William Strahan of November 9, 1776--in which he publicly and explicitly endorsed Hume's skepticism by praising him as a wise and virtuous man, indicating that religious belief was not indispensable for morality, and suggesting that he no longer saw the necessity for esoteric writing, because he lived in a society that was liberal enough to tolerate freedom of thought and speech for philosophers like Hume and himself. He thus became the last esoteric writer and signaled the success of the liberal Enlightenment in making esoteric writing unnecessary and undesirable.
Prior to this letter in 1776, Smith was an esoteric writer. But after this letter, he became more open in his writings, saying things publicly that shocked religious believers, but without suffering violent persecution.
All of these points have been elaborated in previous posts.