The selfish habits of mankind make it difficult to see the true affects of sin. There are many who live by the philosophy that a person should be able to do anything they want so long as it doesn't hurt anyone else. However, the challenge with that way of thinking is that it is rooted in selfishness, which would naturally prohibit one from seeing the affects on others. When one is simply doing what one pleases, there is seldom any attention paid to anyone else to see if anyone is getting hurt. So this logic is flawed and the current condition of the world that seeks to live this way is proof.
The Bible is filled with many examples to prove that sin always has an outward rippling affect on others, whether one acknowledges it or not. In Genesis 20:1-18 the Bible documents Abraham's sin that was packaged in fear and unbelief. Though the Book of Hebrews lists Abraham as one of the historical heroes of faith, there are often times in scripture where Abraham demonstrated his human nature and failed in the department of faith. The sad thing about Genesis 20:1-18 is that Abraham is seen making a mistake that the Bible already showed him making. If one were not paying attention, it would almost seem as if the Bible is repeating something that already happened in Genesis chapter 12. This is not the case. The Bible is simply candid to show the natural flaws of mankind - even God's chosen people.
Genesis 20:1-18 explains that Abraham traveled to the region of the Negev in order to settle there for a while. During the time that Abraham was there, the Bible explains that Abraham made assessments about the spiritual condition of the people in the area, and so asked his wife Sarah to lie about being his wife again. Abraham and Sarah agreed that Sarah would deny being Abraham's wife and state that she was his sister. Though this was a half truth (Sarah was Abraham's step-sister), the scriptures show that the intents of Abraham were to be deceptive. The Bible explains that Abraham examined the people in the area, determined in his mind that they were godless people, and that as godless people, they would kill him to take Sarah if they found out she was his wife. Abraham proves himself to have quite the imagination!
The Bible explains that because of Abraham's flawed assessment of the people, he operated in fear and unbelief. Though God had made and confirmed 3 everlasting promises, Abraham still was fearful of circumstances so that he had to be dishonest to protect himself. The scriptures show that Abraham was less concerned about Sarah and more concerned about himself. The scriptures show that Abraham and Sarah were less concerned about the people in the area and was more concerned about himself. The scriptures explain that the king in the area who held the title Abimelech took Sarah as his own when he found out she was single. Upon taking her as a wife and keeping her in his home, Abimelech had a dream in which the Lord God visited him. The Bible explains that God warned Abimelech that Sarah was a married woman, and that Abimelech should return her to Abraham immediately, otherwise God promised to destroy Abimelech and the people. In terrible fear, Abimelech stated his innocence to the matter and agreed to do as God said. The next morning, Abimelech returned Sarah to Abraham.
The scriptures show that Abraham's sin caused a number of problems for others. Abraham, in his effort to care for himself and do what was good for him, put his wife in a position of compromise, and the people with Abimelech in positions of harm in the eyes of God. The unbelief of Abraham put Sarah and Abimelech in positions of risk concerning the Living God. It was because of Abraham's fear and desire to protect himself without the consideration of others that Sarah was put in a position where she might have been adulterous. It was because of Abraham's fear and desire to protect himself without the consideration of others that Abimelech was visited by God and warned to send Sarah back to Abraham or he and the people would be destroyed.
The interesting thing about the presentation of Abraham's selfishness and foolishness is that, when God was speaking to Abimelech, He referred to Abraham as His prophet. Though Abraham's selfishness and inconsideration was a major mistake, God did not change the way He viewed Abraham. God's grace was greater that Abraham's flaws. This is a beautiful truth to consider. It is true that Abraham's decision to do that which was good for him affected more people than just him. His sin had a rippling affect so that an entire nation of people almost suffered the judgment of God. Therefore, one cannot assume that one's decisions will not have outward affects on others. Whether the affects are adverse or not, one must always consider that one's decisions will have some sort of consequence that affects others in some way. When one operates in sin like Abraham, the consequences are more likely to be harmful. Nonetheless, the Living God is gracious and merciful, so that there are times where greater consequences for sin should manifest, but God restricts the full affects in order that His promises might be fulfilled. In other words, Abraham's situation could have been a lot worse had it not been for the grace of God. In fact the scriptures show that, since God is faithful to Himself to fulfill His promises towards Abraham, Abraham was sent away from Abimelech with more money, more resources, and more influence. God used the foolishness of Abraham as a tool to lead Abraham closer to the fulfillment of His promises. So in the end, the Bible plainly shows once again that people have major flaws that require a Savior from the destruction that our flaws cause; God continues to reveal Himself as that Savior according to His promises.