Stephen explains how the law was given by angels (sons of God) and how the Israelites resisted it.

Acts 7
37 This is that Moses, which said unto the children of Israel, A prophet shall the Lord your God raise up unto you of your brethren, like unto me; him shall ye hear. 38 This is he, that was in the church in the wilderness with the angel which spake to him in the mount Sina, and with our fathers: who received the lively oracles to give unto us: 39 to whom our fathers would not obey, but thrust him from them, and in their hearts turned back again into Egypt, 40 saying unto Aaron, Make us gods to go before us: for as for this Moses, which brought us out of the land of Egypt, we wot not what is become of him. 41 And they made a calf in those days, and offered sacrifice unto the idol, and rejoiced in the works of their own hands. 42 Then God turned, and gave them up to worship the host of heaven; as it is written in the book of the prophets, O ye house of Israel, have ye offered to me slain beasts and sacrifices by the space of forty years in the wilderness? 43 Yea, ye took up the tabernacle of Moloch, and the star of your god Remphan, figures which ye made to worship them: and I will carry you away beyond Babylon.
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51 Ye stiffnecked and uncircumcised in heart and ears, ye do always resist the Holy Ghost: as your fathers did, so do ye. 52 Which of the prophets have not your fathers persecuted? and they have slain them which shewed before of the coming of the Just One; of whom ye have been now the betrayers and murderers: 53 who have received the law by the disposition of angels, and have not kept it.

The below is a source for the above speech by Stephen. An idol to Moloch was built, but Moloch is simply the Sin Bull from Babylon adapted for the Canaanites. The worship of Moloch involved "sinning" (i.e. "play", which connotes sin of sexual nature).

Exodus 32
And when the people saw that Moses delayed to come down out of the mount, the people gathered themselves together unto Aaron, and said unto him, Up, make us gods, which shall go before us; for as for this Moses, the man that brought us up out of the land of Egypt, we wot not what is become of him. 2 And Aaron said unto them, Break off the golden earrings, which are in the ears of your wives, of your sons, and of your daughters, and bring them unto me. 3 And all the people brake off the golden earrings which were in their ears, and brought them unto Aaron. 4 And he received them at their hand, and fashioned it with a graving tool, after he had made it a molten calf: and they said, These be thy gods, O Israel, which brought thee up out of the land of Egypt. 5 And when Aaron saw it, he built an altar before it; and Aaron made proclamation, and said, To morrow is a feast to the Lord. 6 And they rose up early on the morrow, and offered burnt offerings, and brought peace offerings; and the people sat down to eat and to drink, and rose up to play.

7 And the Lord said unto Moses, Go, get thee down; for thy people, which thou broughtest out of the land of Egypt, have corrupted themselves: 8 they have turned aside quickly out of the way which I commanded them: they have made them a molten calf, and have worshipped it, and have sacrificed thereunto, and said, These be thy gods, O Israel, which have brought thee up out of the land of Egypt. 9 And the Lord said unto Moses, I have seen this people, and, behold, it is a stiffnecked people: