Idols
Paul was writing to new Christians living in a non-Christian world.
It was common to make graven images or idols.
Paul may also have been thinking of the time when Aaron made the golden calf at Israel's request when they rebelled against God. God had said do not make molten idols.
In Egypt people made molten idols to worship. So the people asked Aaron to make one.
Romans was written approximately AD57 and was Paul's sixth letter.
Background Reading:
Romans 1:18-25
God's Wrath Against Mankind
18 The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness, 19 since what may be known about God is plain to them, because God has made it plain to them. 20 For since the creation of the world God's invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that men are without excuse.
21 For although they knew God, they neither glorified him as God nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened. 22 Although they claimed to be wise, they became fools 23 and exchanged the glory of the immortal God for images made to look like mortal man and birds and animals and reptiles.
24 Therefore God gave them over in the sinful desires of their hearts to sexual impurity for the degrading of their bodies with one another. 25 They exchanged the truth of God for a lie, and worshiped and served created things rather than the Creator—who is forever praised. Amen.
More Information:
Idol
Romans was written by Paul from Corinth December - February AD56-AD57. As his sixth letter and seventh New Testament book.