Abram obeyed the Lord, Faith comes by hearing the word of God (Romans 10: 17) but he did not obey perfectly, because he took his nephew Lot with him.
Many believers make the same mistake. We choose to follow Him, but we hold onto old comforts, as well, convinced that perhaps God is not enough, that He may not be fully trustworthy.
Yet as we grow in grace and knowledge of Him, we find that not only does He supply all of our needs, but that our previous comforts become cumbersome to our walk with God:
"And Abram said unto Lot, Let there be no strife, I pray thee, between me and thee, and between my herdmen and thy herdmen; for we be brethren.
"Is not the whole land before thee? separate thyself, I pray thee, from me: if thou wilt take the left hand, then I will go to the right; or if thou depart to the right hand, then I will go to the left." (Genesis 13: 8-9)
Abram had no reason to second guess his relative. He trusted that God would prosper him, no matter what Lot chose to do.
After Lot left Abram, the Lord expanded his vision:
"And the LORD said unto Abram, after that Lot was separated from him, Lift up now thine eyes, and look from the place where thou art northward, and southward, and eastward, and westward" (Genesis 13: 14)
As we learn to trust God's supply for our lives, we no longer feel compelled to influence other people's decisions. Lot chose Sodom and Gomorrah, an unwise decision based on sight, not faith. Abram walked by faith, and the Lord expanded the vision of blessing in store for the Father of Faith.