Your question points towards the fact that this story can be read satirically. It is important to realise that Washington Irving is updating an archetypal story concerning men trying to deal with the Devil but always losing in the end. One of the earliest examples is the legend of Faust, a sixteenth century philosopher who sells his soul to the devil for knowledge and power but eventually is claimed by the devil for his own and taken down to hell to suffer for eternity.
If we think of this story as a satire, then, it is clear that Irving is mocking greed, stinginess, religious intolerance, spiritual hypocrisy and the inhumane treatment of others. He criticises the Puritans for their persecution of Quakers and Anabaptists, the Salem witch trials, and their practice of usury - lending money at exorbitant interest. Irving is therefore providing us with an updated version of this classic archetype to show how the Devil may not be too far from America and the exploits of its population. Note what the Devil says to Tom:
"Since the red men have been exterminated by you white savages, I amuse myself by presiding at the persecutions of Quakers and Anabaptists; I am the great patron and prompter of slave dealers, and the grand master of the Salem witches."
Therefore, through this tale Irving is satirically providing a comment on Puritans and their exploits in the new land, which ironically they thought would allow them to get closer to God.