Summary: Here is a very short teaching on what confessing means in regard to 1 John 1:9
1 John 1:9 says, "If we confess our sins, He is faithful and just and will forgive us our sins and will purify us from all unrighteousness." Over the years, many revivals have happened when God poured out His Holy Spirit so mankind may have the opportunity to be restored back into fellowship with Him. At these revivals, this wonderful passage of Scripture has been quoted, so mankind may confess their sins to the Lord -- not publically so to be mocked. Some have been enlightened to God's forgiveness. They are enabled by the Holy Spirit to overcome the sins that held them captive, thus walking in the freedom to live for the Lord. Sadly, many more have walked away from the foot of the cross, only to be overtaken by the sin they just confessed, thus becoming enslaved to do harm to their own soul, hurt others and break the Heart of God.
What is true confession which allows the repentant sinner to fully enjoy God's forgiveness and purification from sin?
The key passage above was written by the apostle John, he instructs Christians on what to do when sin overcomes them as well as sharing the benefits of confession to the Lord. It begins with true confession: "confess" (homologeo - ?µ????e?) means to agree with another or rather to agree with God in regards to the implication of the sin committed by a child of God. This includes the hatred of that sin, the Christian's sense of guilt because of it and his heart's desire to purge that sin out of his life. (Wuest's Word Study in the Greek New Testament; Word Studies in the New Testament) There is a big difference between being sorry and being repentant because of the circumstances one finds himself in because of sin and being broken by the fact your sin had hurt someone else and the Lord.
The Bible tells of the lives of two men: King Saul and King David. King Saul was the king asked for by the people, however, he lacked the spiritual quality to be a successful leader. He was a man who can see the hand of God moving. (1 Samuel 24:20) He confessed his sin; (1 Samuel 26:21) however, his character reflected the heart of a man who would repeatedly disobey the Word of God. (Who's Who in the Bible; 1 Samuel 13;15) There are people who can see God working in their lives, they even confess their sin, but their love of sin causes them to regularly disobey God's word and miss His will for them. These people can never enjoy God's purifying work and they end up living a defeated life.
After removing Saul from his kingship, God made David king, saying, "I found David [to be] a man after My own heart; he will do everything I want him to do." (Acts 13:22) David was a man who had committed many sins. After one of David's embarrassing flesh-pleasuring sins, God told David through the prophet Nathan, "...you have shown utter contempt for the Lord." These words pushed David to become truly broken before the Lord. We read of David's true repentance in Psalm 51, "...Wash away all my iniquity and cleanse me from my sin." (Psalm 51:2)