In Hawthorne's indictment against secret sin and the psychological effects of sin, The Scarlet Letter, the Reverend Arthur Dimmesdale commits sins against the Ten Commandments; also, he commits one of the Cardinal, or Seven Deadly Sins. Because Reverend Dimmesdale is a Puritan minister, the commandments that he violates, in accord with the Protestant version, are #7 "Thou shalt not commit adultery" and #9 "Thou shalt not bear false witness." The Cardinal sin that he commits is the sin of Pride.
As Hawthorne's narrative progresses, it becomes apparent to the reader that Dimmesdale is tortured by some inner conflict in his soul. Certainly, Roger Chillingworth suspects him of being his wife's paramour as he stealthily ingratiates himself into the minister's home and continually questions the minister about what troubles him. When Chillingworth dances in delight one night in Chapter X after pulling away the minister's vestment and detecting an identifying mark of this sin of adultery upon the chest of Arthur Dimmesdale, it is also evident that harboring this sin in secret has taken a terrible toll upon the minister.
Because he hides his sin, lacking the fortitude to confess and bring scandal upon himself, Arthur Dimmesdale lives a lie. Thus, whatever he says is tainted by his falsity. For, even when he attempts confession of his unworthiness, his congregation believes that he has saintly humility since they are unaware of his secret sin. Predicated upon his withholding his original sin of adultery secret from people, all Dimmesdale's further words are, therefore, hollow and deceptive.
The Reverend Dimmesdale proudly convinces himself that he is generating more good in continuing God's work than if he confesses and is removed from the ministry. In Chapter X, Chillingworth and Dimmesdale talk, and in his pride the minister "could not recognize his enemy when the latter actually appeared." Also, Dimmesdale offers his rationalized perspective to the physician, telling him that the heart that holds secrets must wait "until the day when all hidden things shall be revealed," Judgment Day. Further, in his pride Dimmesdale speaks of the good that a sinner can do by sharing his suffering with others:
"It may be that they are kept silent by the very constitution of their nature. Or--can we not suppose it--guilty as they may be, retaining, nevertheless, a zeal for God's glory and man's welfare, they shrink from displaying themselves black and filthy in the view of men; because, thenceforward, no good can be achieved by them; no evil of the past be redeemed by better service."
Truly, the "concealed sins" of pride and falseness are greater than Dimmesdale's sin of adultery. For, it is these sins, above all others, that Hawthorne excoriates in statement of theme in Chapter XXIV, "Conclusion,"
"Be true! Be true! be true! Show freely to the world, if not your worst, yet some trait whereby the worst may be inferred!"
In The Scarlet Letter by Nathaniel Hawthorne, the Reverend Arthur Dimmesdale is a minister in a strongly Calvinist church. At sometime before the novel begins, he has had an affair with Hester Prynne, a woman who was married to Roger Chillingworth. Thus is main sin is adultery. The sin in a sense is both caused by and causes two other moral failings. First, he is a hypocrite, in that he continues to preach a Gospel condemning such sins as lying and adultery despite having commmitted both himself. Second, he is morally weak but still has the sort of pride which prevents him from confessing his sins to 'God and neighbor' as he should until the end of the novel.