It is narrated on the authority of Abu Huraira: A fornicator who fornicates is not a believer as long as he commits fornication, and no one who steals is a believer as long as he commits theft, and no one who drinks wine is a believer as long as he drinks it, and repentance may be accepted after that.  (Muslim)

Lessons to learn from this Hadith

1. Prophet (saw) is telling us that a person cannot be a  believer at the time when he is fornicating, stealing or drinking wine.
2. Ihsan is lacking at the time of committing the sin. He is guilty of sin. He is not a disbeliever. He is a sinful believer.
3. If he repents, then Allah may forgive him. But if he dies without repenting, then Allah will judge whether to forgive him or not.

Conditions for Repentance:

1. Repentance varies according to the sin.
2. Refrain from the sin completely and the ways it leads oneself to the sin.
3. Feeling deep remorse. We should feel guilty.
4. Firm determination not to return back to the sin.

Good deeds wipe our bad deeds. Do extra good deeds so that our bad deeds can be forgiven by Allah.

If we Backbite:

1. If we can ask forgiveness from that person, then we should ask for forgiveness.
2. If we cannot ask for forgiveness from that person, then next time when his name is taken, tell something good about him.
3. Give charity on his behalf.
4. Ask forgiveness from Allah.