The existence of religions throughout history could be seen as a big problem for the atheist. It may well look like man is naturally inclined to believe in the supernatural or spiritual. If the atheist is right and there is no god, then how do they account for past societies and cultures who did believe in the supernatural or a deity? Hume sets out to say religion "springs from the essential and universal properties of human nature" (which may well sound like man is naturally inclined to believe in God).
The primary religion of mankind arises chiefly from an anxious fear of future events... (page 26)The problem with the god/s of religions:
Here therefore is a kind of contradiction between the different principle of human nature, which enter into religion. Our natural terrors present the notion of a devilish and malicious deity: Our propensity to adulation leads us to acknowledge an excellent and divine. (page 27)Hume continues to say that religion makes people immoral:
...as men farther exalt their idea of their divinity; it is their notion of his power and knowledge only, not of his goodness, which is improved. (page 27)
...in every religion, however sublime the verbal definition which it gives of its divinity, many of the votaries... will still seek the divine favour, not by virtue and good morals, which alone can be acceptable to a perfect being, but either by frivolous observances, by intemperate zeal, by rapturous ecstasies, or by the belief of mysterious and absurd opinions. (page 28)Hume cites the Greek gods to show that they were very human and didn't even behave as well as the people on earth. To which I agree. Back in the day they didn't have Neighbors or Home and Away, and their society needed some cultural drama to keep them entertained...
Hence the greatest crimes have been found, in many instances, compatible with a superstitious piety and devotion; Hence, it is justly regarded as unsafe to draw any inference in favour of a man’s morals, from the fervour or strictness of his religious exercises, even though he himself believes them sincere. (page 30)
...while we abandon ourselves to the natural undisciplined suggestions of our timid and anxious hearts, every kind of barbarity is ascribed to the supreme Being... The more tremendous the divinity is represented, the more tame and submissive do men become his ministers: And the more unaccountable the measures of acceptance required by him, the more necessary does it become to abandon our natural reason, and yield to their ghostly guidance and direction. (page 31)
Hume sees the attempt to gain God's favor as an unworthy goal. He rightly asks: how does fasting or whipping yourself make yourself better in the eyes of God and assure you eternal happiness?
Hume says the monotheistic god's have more power but don't actually have more goodness (which very much does sound like an idea of God that is based off humans). It sounds like Hume would like to believe in a God that is all powerful and also all good. A God that isn't given into immorality like the Greek gods (for example who doesn't lie). A God that has incommunicable attributes, which would then mean God would have to reveal Himself to us as we would not be able to understand Him on our own. Also Hume would like a God who's followers promote the idea that they are to love their neighbors, looks after the poor and the widowed and the orphans.
You can read all of The Natural History of Religion here.