Abram dwelt in the land of Canaan, and Lot dwelt in the cities of the plain and pitched his tent as far as Sodom. Genesis 13:12 (NKJV)
This is where each of them dwelt, but let me briefly take you back before they separated. Abram took his wife and all that they had on a journey south as far as Bethel. Lot (his nephew) also went with Abram along with his flocks herds and tents. The land between Bethel and Ai was not able to support them that they dwell together, for their possessions were great.
Their was strife between the herdsman of Abram's livestock and the herdsmen of Lot's livestock. So, Abram said to Lot, Please let there be no strife between you and I or between my herdsmen and your herdsmen. Please separate from me, Abram told Lot. Then Lot chose the plain of Jordan because he could see that it was well watered. (Looks can be deceiving) Later there would be many battles and he would be taken captive.
After they separated simply because it was time. The Lord told Abram, all the land that you can see I will give to you and your descendants forever. Lot would later be rescued by Abram.
Even though some of our associations chase after what appears to look good it can also lead them down a path of destruction. Despite some of our associations we are currently around, not all of them are beneficial to God's plan for us. After trying our own methods to rescue others sometimes it is best to simply separate ourselves from them.
When trying to help others who are on a path of destruction at times it is best if we do this from afar. I believe God will bless us as we intercede for them through prayer. After all, prayer is very powerful and it allows God to work through us. At the same time we know God is protecting us and fighting on our behalf. After we have done all we can God is sure to finish it.
Who knows maybe God will use us later on to be part of the rescue mission just as He used Abram to rescue Lot. In the meantime, allow God to do what only He can do. Then if or when He wants us to step back in we should be wiling to assist them in the way God tells us to.