Sincerity is not what redeems us, we often try to maintain our confidence by looking inward for personal enthusiasm. The reality is that strong faith often feels l like profound weakness and yet it proves itself by its perseverance. Paul was very sincere before he was a Christian, he was sincere in his error and yet his sincerity would not have saved him. Paul had many credentials and had a high status in religious society before he was saved and yet he counted all of those things as 'dung' compared to knowing Christ.