I just want to make mention that the letter written in much "affliction and anguish" is not the letter of 1 Corinthians, but one of the two letters that are not published in the Bible.
In verses 6-8, Paul is addressing a specific concern within the Corinth church regarding a man who had apparently done wrong, was punished, and now needed forgiveness and love.
Since we have been forgiven by Jesus, we also as Christians, must forgive. When we don't forgive and hold bitterness, anger, or resentment toward another believer, we are allowing Satan to break unity among the church body. Satan's design is to ruin relationships, love and unity between people and especially between a person and God.
The term "aroma of Christ" refers to the pleasing aroma arising from a sacrifice presented to God, practiced in the old testament. When someone burned a sacrifice to God, it would often say the aroma was pleasing. Since Christ is the ultimate sacrifice and Paul is 'sacrificing' his life in full time ministry for Christ, he is stating that his work presents the aroma of Christ- to all those whom he comes in contact with- believers and unbelievers.
For we are the aroma of Christ to God among those who are being saved and among those who are perishing...