What does Genesis 18:28 mean?
Abraham begins bargaining with the Lord in earnest now. In the previous verses, Abraham declared that the Lord could not, in good character, sweep away the city of Sodom if some of the residents were righteous. We know Abraham's nephew Lot lived in the city (Genesis 14:12). Abraham started by asking, what if 50 righteous people live in the city? The Lord stated flatly that He would not destroy the city if He found 50 righteous people.This "negotiation," of course, is merely for the benefit of Abraham and the rest of mankind. God has no obligation to discuss this decision with anyone. However, like a patient teacher, God allows Abraham to "talk out" the situation. When all is said and done, this will only go to prove how truly justified God's wrath against Sodom truly is.
After getting a positive answer from God about sparing the city for the sake of a few people, Abraham continues to work a strategy to talk the Lord down to the smallest number of people possible. Here the Lord agrees not to destroy the city if He finds 45 righteous people. Abraham's intent, most likely, is to plead for the rescue of his nephew, Lot, who lives in Sodom.
It's important to note here that the word "righteous," as used by Abraham, does not mean sinlessly perfect people. In an Old Testament context, this term refers to those who don't participate in the grave sins openly practiced in Sodom and Gomorrah. Those sins included rape, sexual immorality including homosexuality, gluttony, and not caring for or helping the poor (Genesis 19; Ezekiel 16:49–50).