Why did the Israelites worship a golden calf in Exodus 32?

from the old testament

• Exodus 32 records the infamous account of the Israelites and the golden calf. Moses was on Mount Sinai meeting with God. When the people saw that Moses was not coming down yet, they called for Aaron to make them gods that would go before them (Exodus 32:1). Aaron instructed the people to remove their gold jewelry and to bring it to him. They did so, and he "fashioned it with a graving tool and made a golden calf. And they said, 'These are your gods, O Israel, who brought you out of the land of Egypt!'" (Exodus 32:4). Aaron built an altar in front of it and declared a feast the following day.
• God knew what the people had done and told Moses, "Go down, for your people, whom you brought up out of the land of Egypt, have corrupted themselves. They have turned aside quickly out of the way that I commanded them" (Exodus 32:7–8). God’s wrath burned hot against the people for their idolatry (Exodus 32:10). Moses, who foreshadowed Jesus, interceded for the Israelites. He spoke of God's reputation before the Egyptians as well as God's promise to Abraham, Isaac, and Jacob. "And the LORD relented from the disaster that he had spoken of bringing on his people" (Exodus 32:14).
• When Moses came down the mountain, he saw the people worshiping the golden calf; Moses was angry and he broke the tablets on which God had engraved the covenant He'd given Moses on Sinai. Moses burned the golden calf and ground it into a powder, which he mixed with water and gave the people to drink. He rebuked Aaron and called for the people who would choose the Lord to come to him. The Levites did so, and Moses instructed them to strike down the Israelites who were worshiping the golden calf. About three thousand men were killed that day (Exodus 32:15–29).
• Moses told the people, "You have sinned a great sin. And now I will go up to the LORD; perhaps I can make atonement for your sin" (Exodus 32:30). Moses confessed the people's sin to God and asked Him to forgive them, asking God to kill him if He would not forgive the people. "But the LORD said to Moses, 'Whoever has sinned against me, I will blot out of my book. But now go, lead the people to the place about which I have spoken to you; behold, my angel shall go before you. Nevertheless, in the day when I visit, I will visit their sin upon them'" (Exodus 32:33–34).
• After God led the Israelites from captivity in Egypt, they faced a variety of hardships. Living in the desert is not easy. They suffered hunger and thirst (Exodus 16:1–3; 17:3). They doubted God's goodness (Exodus 17:7). They were uncertain about Moses (Exodus 15:24; Numbers 14:1–4; 16:1–11). It seems the Israelites wanted something more tangible, perhaps even a god over which they felt they had more control.
• Interestingly, it was golden calves that Jeroboam chose as idols to place in Bethel and Dan when the kingdom of Israel divided centuries later (1 Kings 12). He said, "You have gone up to Jerusalem long enough. Behold your gods, O Israel, who brought you up out of the land of Egypt" (1 Kings 12:28). In doing this, Jeroboam greatly sinned against the Lord.

from the new testament

• The golden calf incident is not mentioned in the New Testament.
• Moses, who mediated for the Israelites, is seen as a type of Christ. Jesus is the true mediator between God and humans (1 Timothy 2:5–6; Hebrews 3:1–6; 10:1–18).
• The New Testament warns against idolatry and emphasizes the worship of the One true God (1 Corinthians 10:14; Colossians 3:5; 1 John 5:21).

implications for today

God doesn't always tell us what He's doing. Very rarely can we see the steps ahead. When things are uncertain, it can be tempting to trust something else instead. When we are afraid, we can try to put our trust in something over which we feel some degree of control or in something that seems predictable—perhaps money, our own strength, our intelligence, a sense of normalcy, an organization, or another person. The idol itself is not the point. The point is that idolatry—worshiping and trusting in something other than God—is a sin and cannot save you. We, too, can build gods of our own that do not reflect the true God of the Bible. We might start a "quid pro quo" relationship with this god, thinking that if we do one thing, it will be bound to respond the way we want. This dynamic is called "appeasing the gods" and it exists in every religion on earth.

Yahweh, the true God and Creator, is different. He doesn't require or ask for appeasement (Matthew 11:28; Romans 4:4–5). He doesn't require us to do good things in exchange for His love (John 3:16–18; Romans 3:21–24). He wants us to pursue good things because they are good. We aren't asked to save ourselves with good behavior or with good works. Instead, we are asked to confess our inability to save ourselves and to trust in God’s power for our justification and sanctification (Romans 1:16; 1 John 1:9; Hebrews 10:10, 14).

We are dead in our sins and can only be rescued by God's grace through faith in Jesus (Ephesians 2:1–10). When we are saved, we become God's child and enter a dynamic relationship with Him, even receiving the indwelling of the Holy Spirit (John 1:12; Ephesians 1:13–14). This God could never be encapsulated in the image of a golden calf. A mere idol—golden or intangible—could never accomplish the works God does or love us with the complete love He does (Romans 8:31–39; Ephesians 3:14–21).