Joshua 8:1
"And the LORD said unto Joshua, Fear not, neither be thou dismayed: take all the people of war with thee, and arise, go up to Ai: see, I have given into thy hand the king of Ai, and his people, and his city, and his land:"
Israel found out first hand the negative impact sin has on success. They had just experienced two major victories with the crossing of the Jordan River and the conquering of Jericho, but sin quickly squelched their success when they came to the small city of Ai. In the verse above, God was trying to reverse the negative impact sin had on Israel by challenging them to go and take the city now that sin was removed. In God's encouragement to these people, you find the negative impact sin has on one's success.
First, sin causes a person to fear. God told them to "fear not" because sin had taken their confidence. One of the hardest things to acquire in life is confidence, but sin will take your confidence and cause you to fear. Sin will keep a person from having the faith to step out and trust God. Sin blinds you from God's presence, and that is why you fear when asked to do something by faith. Ai was just a little city, but they didn't even have the confidence to conquer that city because of fear. Sin will amazingly cause once great Christians to cower at the expectations of faith. You must be careful that sin doesn't replace your confidence with fear.
Second, sin causes a person to live with stress. God also said to Israel, "...neither be thou dismayed..." Israel was dismayed because of the stress sin gave them. You will always find that those living in sin live a stress-filled life. If you want to remove stress from your life, then you would be wise to remove sin. Because sin causes a person to fear, stress at the prospect of stepping out by faith will set in.
Third, sin will take a person's drive from them. It is interesting that God challenged Israel to "arise." They lost their drive to conquer because of the fear and stress. One of the key ingredients of success is personal drive. A person who is driven is a person who overcomes any obstacle until they succeed. You will find that sin takes that drive away. Where once a person used to be self-motivated, sin takes that motivation away and causes them to settle short of their potential. The only way to get the drive to reach your potential is to remove sin from your life.
Fourth, sin causes a person to have poor judgment. What is not seen in the verse above is Isreal's poor judgment concerning the battle of Ai the first time. Sin always clouds a person's judgment so that they cannot clearly see what they should be doing. Many people have never achieved success because of their poor judgment.
Friend, the negative impact that sin will have on your life is tremendous. It will turn you into a fearful person who lives a stress-filled life with no drive to go after God's will. Don't let sin do that to you. Remove whatever sin you may have in your life. Don't let sin rob you of your potential and success.