‘Abram dwelt in the land of Canaan, and Lot dwelt in the cities of ‘the Circle' and moved his tent as far as Sodom. Now the men of Sodom were wicked and great sinners against Yahweh.'
There is no doubt that the writer sees the significance of their choices. The one remaining in the place allotted by God, the other unconsciously approaching grave danger because his eyes feast on what seems so wonderful. He forgets the promises of God. He approaches Sodom. What more needs to be said? For Sodom is a centre of wickedness and sexual depravity (see Ezekiel 16:48-50 - where ‘pride' and ‘fullness of bread with prosperous ease' are said to be at the root of her sins). Note that although they are not worshippers of Yahweh their sin is said to be against Him. He is judge over all and has the right to obedience from all.
This description of Sodom is partially preparing us for what is to happen to Sodom in chapter 14. He is already preparing us for this, and giving us an explanation as to why Lot is involved in such a catastrophe. Those who consort with sinners must not complain when they share the consequences of their judgment. Connection with cities was regularly seen as a downward step.
But note also the continuing theme of Genesis 4:10; Genesis 4:11. Abram dwelt in ‘the land', Lot dwelt in ‘the cities'. It is a recurring theme that as men become involved with ‘civilisation', with its prosperity and opportunities for sin, they become involved with its ways and forget God.
“Moved his tent.” This is in contrast with ‘pitched his tent' (Genesis 12:8). Bethel (the house of God) had been their centre, but now Lot moves his centre to Sodom. How many have done a similar thing and suffered thereby. Indeed, as we learn later, he takes up abode in Sodom and becomes an important man among them (Genesis 19:2-3). (This incidentally draws attention to the fact that the way of life of the family of Terah does not exclude dwelling in a city. Thus it may well be that Abram once dwelt with his family in a house in Ur rather than just camping outside. For Terah was involved in the religion of Ur).